Adding upstream version 1:115.7.0.upstream/1%115.7.0upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 7411 insertions, 0 deletions

diff --git a/comm/mailnews/base/src/nsMsgDBView.cpp b/comm/mailnews/base/src/nsMsgDBView.cpp
new file mode 100644
index 0000000000..6532b52e0e
--- /dev/null
+++ b/comm/mailnews/base/src/nsMsgDBView.cpp
@@ -0,0 +1,7411 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include <algorithm>
+#include "msgCore.h"
+#include "prmem.h"
+#include "nsArrayUtils.h"
+#include "nsIMsgCustomColumnHandler.h"
+#include "nsMsgDBView.h"
+#include "nsISupports.h"
+#include "nsIMsgFolder.h"
+#include "nsIDBFolderInfo.h"
+#include "nsIMsgDatabase.h"
+#include "nsIMsgFolder.h"
+#include "MailNewsTypes2.h"
+#include "nsIMsgImapMailFolder.h"
+#include "nsImapCore.h"
+#include "nsMsgFolderFlags.h"
+#include "nsIMsgLocalMailFolder.h"
+#include "nsIPrefService.h"
+#include "nsIPrefBranch.h"
+#include "nsIPrefLocalizedString.h"
+#include "nsIMsgSearchSession.h"
+#include "nsIMsgCopyService.h"
+#include "nsISpamSettings.h"
+#include "nsIMsgAccountManager.h"
+#include "nsTreeColumns.h"
+#include "nsTextFormatter.h"
+#include "nsIMimeConverter.h"
+#include "nsMsgMessageFlags.h"
+#include "nsIPrompt.h"
+#include "nsIWindowWatcher.h"
+#include "nsIMsgFolderNotificationService.h"
+#include "nsServiceManagerUtils.h"
+#include "nsComponentManagerUtils.h"
+#include "nsMemory.h"
+#include "nsIAbManager.h"
+#include "nsIAbDirectory.h"
+#include "nsIAbCard.h"
+#include "mozilla/Components.h"
+#include "mozilla/Attributes.h"
+#include "mozilla/dom/DataTransfer.h"
+#include "mozilla/mailnews/MimeHeaderParser.h"
+#include "nsTArray.h"
+#include "mozilla/intl/OSPreferences.h"
+#include "mozilla/intl/LocaleService.h"
+#include "mozilla/intl/AppDateTimeFormat.h"
+
+using namespace mozilla::mailnews;
+
+nsString nsMsgDBView::kHighestPriorityString;
+nsString nsMsgDBView::kHighPriorityString;
+nsString nsMsgDBView::kLowestPriorityString;
+nsString nsMsgDBView::kLowPriorityString;
+nsString nsMsgDBView::kNormalPriorityString;
+
+nsString nsMsgDBView::kReadString;
+nsString nsMsgDBView::kRepliedString;
+nsString nsMsgDBView::kForwardedString;
+nsString nsMsgDBView::kRedirectedString;
+nsString nsMsgDBView::kNewString;
+
+nsString nsMsgDBView::kTodayString;
+nsString nsMsgDBView::kYesterdayString;
+nsString nsMsgDBView::kLastWeekString;
+nsString nsMsgDBView::kTwoWeeksAgoString;
+nsString nsMsgDBView::kOldMailString;
+nsString nsMsgDBView::kFutureDateString;
+
+bool nsMsgDBView::m_dateFormatsInitialized = false;
+nsDateFormatSelectorComm nsMsgDBView::m_dateFormatDefault = kDateFormatShort;
+nsDateFormatSelectorComm nsMsgDBView::m_dateFormatThisWeek = kDateFormatShort;
+nsDateFormatSelectorComm nsMsgDBView::m_dateFormatToday = kDateFormatNone;
+
+nsString nsMsgDBView::m_connectorPattern;
+nsCOMPtr<nsIStringBundle> nsMsgDBView::mMessengerStringBundle;
+
+static const uint32_t kMaxNumSortColumns = 2;
+
+static void GetCachedName(const nsCString& unparsedString,
+                          int32_t displayVersion, nsACString& cachedName);
+
+static void UpdateCachedName(nsIMsgDBHdr* aHdr, const char* header_field,
+                             const nsAString& newName);
+
+// viewSortInfo is context data passed into the sort comparison functions -
+// FnSortIdUint32 for comparing numeric fields, FnSortIdKey for everything
+// else. If a comparison function finds two elements with equal primary
+// ordering, it'll call SecondaryCompare() to break the deadlock.
+// SecondaryCompare() uses the same comparison functions again, but using the
+// secondary key and potentially with different criteria (eg secondary sort
+// order might be different to primary). The viewSortInfo::isSecondarySort
+// flag lets the comparison function know not to call SecondaryCompare()
+// again (and again and again)...
+class viewSortInfo {
+ public:
+  nsMsgDBView* view;
+  nsIMsgDatabase* db;  // Which db to use for collation compares.
+  bool isSecondarySort;
+  bool ascendingSort;
+};
+
+NS_IMPL_ISUPPORTS(nsMsgDBViewService, nsIMsgDBViewService)
+NS_IMETHODIMP nsMsgDBViewService::InitializeDBViewStrings() {
+  nsMsgDBView::InitializeLiterals();
+  nsMsgDBView::m_connectorPattern.Truncate();
+  nsMsgDBView::mMessengerStringBundle = nullptr;
+  // Initialize date display format.
+  if (!nsMsgDBView::m_dateFormatsInitialized) {
+    nsMsgDBView::InitDisplayFormats();
+  }
+  return NS_OK;
+}
+
+NS_IMPL_ADDREF(nsMsgDBView)
+NS_IMPL_RELEASE(nsMsgDBView)
+
+NS_INTERFACE_MAP_BEGIN(nsMsgDBView)
+  NS_INTERFACE_MAP_ENTRY_AMBIGUOUS(nsISupports, nsIMsgDBView)
+  NS_INTERFACE_MAP_ENTRY(nsIMsgDBView)
+  NS_INTERFACE_MAP_ENTRY(nsIDBChangeListener)
+  NS_INTERFACE_MAP_ENTRY(nsITreeView)
+  NS_INTERFACE_MAP_ENTRY(nsIJunkMailClassificationListener)
+NS_INTERFACE_MAP_END
+
+nsMsgDBView::nsMsgDBView() {
+  // Member initializers and constructor code.
+  m_sortValid = false;
+  m_checkedCustomColumns = false;
+  m_sortOrder = nsMsgViewSortOrder::none;
+  m_sortType = nsMsgViewSortType::byNone;
+  m_viewFlags = nsMsgViewFlagsType::kNone;
+  m_secondarySort = nsMsgViewSortType::byId;
+  m_secondarySortOrder = nsMsgViewSortOrder::ascending;
+  m_cachedMsgKey = nsMsgKey_None;
+  m_currentlyDisplayedMsgKey = nsMsgKey_None;
+  m_currentlyDisplayedViewIndex = nsMsgViewIndex_None;
+  mNumSelectedRows = 0;
+  mSuppressMsgDisplay = false;
+  mSuppressCommandUpdating = false;
+  mSuppressChangeNotification = false;
+  mSummarizeFailed = false;
+  mSelectionSummarized = false;
+
+  mIsNews = false;
+  mIsRss = false;
+  mIsXFVirtual = false;
+  mDeleteModel = nsMsgImapDeleteModels::MoveToTrash;
+  m_deletingRows = false;
+  mNumMessagesRemainingInBatch = 0;
+  mShowSizeInLines = false;
+  mSortThreadsByRoot = false;
+
+  // mCommandsNeedDisablingBecauseOfSelection - A boolean that tell us if we
+  // needed to disable commands because of what's selected. If we're offline
+  // w/o a downloaded msg selected, or a dummy message was selected.
+  mCommandsNeedDisablingBecauseOfSelection = false;
+  mRemovingRow = false;
+  m_saveRestoreSelectionDepth = 0;
+  mRecentlyDeletedArrayIndex = 0;
+}
+
+void nsMsgDBView::InitializeLiterals() {
+  // Priority strings.
+  GetString(u"priorityHighest", kHighestPriorityString);
+  GetString(u"priorityHigh", kHighPriorityString);
+  GetString(u"priorityLowest", kLowestPriorityString);
+  GetString(u"priorityLow", kLowPriorityString);
+  GetString(u"priorityNormal", kNormalPriorityString);
+
+  GetString(u"read", kReadString);
+  GetString(u"replied", kRepliedString);
+  GetString(u"forwarded", kForwardedString);
+  GetString(u"redirected", kRedirectedString);
+  GetString(u"new", kNewString);
+
+  GetString(u"today", kTodayString);
+  GetString(u"yesterday", kYesterdayString);
+  GetString(u"last7Days", kLastWeekString);
+  GetString(u"last14Days", kTwoWeeksAgoString);
+  GetString(u"older", kOldMailString);
+  GetString(u"futureDate", kFutureDateString);
+}
+
+nsMsgDBView::~nsMsgDBView() {
+  if (m_db) m_db->RemoveListener(this);
+}
+
+// Helper function used to fetch strings from the messenger string bundle
+void nsMsgDBView::GetString(const char16_t* aStringName, nsAString& aValue) {
+  nsresult res = NS_ERROR_UNEXPECTED;
+
+  if (!nsMsgDBView::mMessengerStringBundle) {
+    static const char propertyURL[] = MESSENGER_STRING_URL;
+    nsCOMPtr<nsIStringBundleService> sBundleService =
+        mozilla::components::StringBundle::Service();
+
+    if (sBundleService)
+      res = sBundleService->CreateBundle(
+          propertyURL, getter_AddRefs(nsMsgDBView::mMessengerStringBundle));
+  }
+
+  if (nsMsgDBView::mMessengerStringBundle)
+    res = mMessengerStringBundle->GetStringFromName(
+        NS_ConvertUTF16toUTF8(aStringName).get(), aValue);
+
+  if (NS_FAILED(res)) {
+    aValue = aStringName;
+  }
+}
+
+// Helper function used to fetch localized strings from the prefs
+nsresult nsMsgDBView::GetPrefLocalizedString(const char* aPrefName,
+                                             nsString& aResult) {
+  nsresult rv = NS_OK;
+  nsCOMPtr<nsIPrefBranch> prefBranch;
+  nsCOMPtr<nsIPrefLocalizedString> pls;
+  nsString ucsval;
+
+  prefBranch = do_GetService(NS_PREFSERVICE_CONTRACTID, &rv);
+  NS_ENSURE_SUCCESS(rv, rv);
+
+  rv = prefBranch->GetComplexValue(
+      aPrefName, NS_GET_IID(nsIPrefLocalizedString), getter_AddRefs(pls));
+  NS_ENSURE_SUCCESS(rv, rv);
+  pls->ToString(getter_Copies(ucsval));
+  aResult = ucsval.get();
+  return rv;
+}
+
+nsresult nsMsgDBView::AppendKeywordProperties(const nsACString& keywords,
+                                              nsAString& properties,
+                                              bool* tagAdded) {
+  *tagAdded = false;
+  // Get the top most keyword's CSS selector and append that as a property.
+  nsresult rv;
+  if (!mTagService) {
+    mTagService = do_GetService("@mozilla.org/messenger/tagservice;1", &rv);
+    NS_ENSURE_SUCCESS(rv, rv);
+  }
+
+  nsCString topKey;
+  rv = mTagService->GetTopKey(keywords, topKey);
+  NS_ENSURE_SUCCESS(rv, rv);
+  if (topKey.IsEmpty()) return NS_OK;
+
+  nsString selector;
+  rv = mTagService->GetSelectorForKey(topKey, selector);
+  if (NS_SUCCEEDED(rv)) {
+    *tagAdded = true;
+    properties.Append(' ');
+    properties.Append(selector);
+  }
+  return rv;
+}
+
+///////////////////////////////////////////////////////////////////////////
+// nsITreeView Implementation Methods (and helper methods)
+///////////////////////////////////////////////////////////////////////////
+
+static nsresult GetDisplayNameInAddressBook(const nsACString& emailAddress,
+                                            nsAString& displayName) {
+  nsresult rv;
+  nsCOMPtr<nsIAbManager> abManager(
+      do_GetService("@mozilla.org/abmanager;1", &rv));
+  NS_ENSURE_SUCCESS(rv, rv);
+
+  nsCOMPtr<nsIAbCard> cardForAddress;
+  rv = abManager->CardForEmailAddress(emailAddress,
+                                      getter_AddRefs(cardForAddress));
+  NS_ENSURE_SUCCESS(rv, rv);
+
+  if (cardForAddress) {
+    bool preferDisplayName = true;
+    rv = cardForAddress->GetPropertyAsBool("PreferDisplayName", true,
+                                           &preferDisplayName);
+
+    if (NS_FAILED(rv) || preferDisplayName)
+      rv = cardForAddress->GetDisplayName(displayName);
+  }
+
+  return rv;
+}
+
+/*
+ * The unparsedString has following format:
+ * "version|displayname"
+ */
+static void GetCachedName(const nsCString& unparsedString,
+                          int32_t displayVersion, nsACString& cachedName) {
+  nsresult err;
+
+  // Get version #.
+  int32_t cachedVersion = unparsedString.ToInteger(&err);
+  if (cachedVersion != displayVersion) return;
+
+  // Get cached name.
+  int32_t pos = unparsedString.FindChar('|');
+  if (pos != kNotFound) cachedName = Substring(unparsedString, pos + 1);
+}
+
+static void UpdateCachedName(nsIMsgDBHdr* aHdr, const char* header_field,
+                             const nsAString& newName) {
+  nsCString newCachedName;
+  nsCOMPtr<nsIPrefBranch> prefs(do_GetService(NS_PREFSERVICE_CONTRACTID));
+  int32_t currentDisplayNameVersion = 0;
+
+  prefs->GetIntPref("mail.displayname.version", &currentDisplayNameVersion);
+
+  // Save version number.
+  newCachedName.AppendInt(currentDisplayNameVersion);
+  newCachedName.Append('|');
+
+  // Save name.
+  newCachedName.Append(NS_ConvertUTF16toUTF8(newName));
+
+  aHdr->SetStringProperty(header_field, newCachedName);
+}
+
+nsresult nsMsgDBView::FetchAuthor(nsIMsgDBHdr* aHdr, nsAString& aSenderString) {
+  nsCString unparsedAuthor;
+  bool showCondensedAddresses = false;
+  int32_t currentDisplayNameVersion = 0;
+  nsCOMPtr<nsIPrefBranch> prefs(do_GetService(NS_PREFSERVICE_CONTRACTID));
+
+  prefs->GetIntPref("mail.displayname.version", &currentDisplayNameVersion);
+  prefs->GetBoolPref("mail.showCondensedAddresses", &showCondensedAddresses);
+
+  aHdr->GetStringProperty("sender_name", unparsedAuthor);
+
+  // If the author is already computed, use it.
+  if (!unparsedAuthor.IsEmpty()) {
+    nsCString cachedDisplayName;
+    GetCachedName(unparsedAuthor, currentDisplayNameVersion, cachedDisplayName);
+    if (!cachedDisplayName.IsEmpty()) {
+      CopyUTF8toUTF16(cachedDisplayName, aSenderString);
+      return NS_OK;
+    }
+  }
+
+  nsCString author;
+  (void)aHdr->GetAuthor(getter_Copies(author));
+
+  nsCString headerCharset;
+  aHdr->GetEffectiveCharset(headerCharset);
+
+  nsString name;
+  nsCString emailAddress;
+  nsCOMArray<msgIAddressObject> addresses =
+      EncodedHeader(author, headerCharset.get());
+  bool multipleAuthors = addresses.Length() > 1;
+
+  ExtractFirstAddress(addresses, name, emailAddress);
+
+  if (showCondensedAddresses)
+    GetDisplayNameInAddressBook(emailAddress, aSenderString);
+
+  if (aSenderString.IsEmpty()) {
+    // We can't use the display name in the card; use the name contained in
+    // the header or email address.
+    if (name.IsEmpty()) {
+      CopyUTF8toUTF16(emailAddress, aSenderString);
+    } else {
+      int32_t atPos;
+      if ((atPos = name.FindChar('@')) == kNotFound ||
+          name.FindChar('.', atPos) == kNotFound) {
+        aSenderString = name;
+      } else {
+        // Found @ followed by a dot, so this looks like a spoofing case.
+        aSenderString = name;
+        aSenderString.AppendLiteral(" <");
+        AppendUTF8toUTF16(emailAddress, aSenderString);
+        aSenderString.Append('>');
+      }
+    }
+  }
+
+  if (multipleAuthors) {
+    aSenderString.AppendLiteral(" ");
+    nsAutoString val;
+    GetString(u"andOthers", val);
+    aSenderString.Append(val);
+  }
+
+  UpdateCachedName(aHdr, "sender_name", aSenderString);
+
+  return NS_OK;
+}
+
+nsresult nsMsgDBView::FetchAccount(nsIMsgDBHdr* aHdr, nsAString& aAccount) {
+  nsCString accountKey;
+  nsresult rv = aHdr->GetAccountKey(getter_Copies(accountKey));
+
+  // Cache the account manager?
+  nsCOMPtr<nsIMsgAccountManager> accountManager(
+      do_GetService("@mozilla.org/messenger/account-manager;1", &rv));
+
+  NS_ENSURE_SUCCESS(rv, rv);
+  nsCOMPtr<nsIMsgAccount> account;
+  nsCOMPtr<nsIMsgIncomingServer> server;
+  if (!accountKey.IsEmpty())
+    rv = accountManager->GetAccount(accountKey, getter_AddRefs(account));
+
+  if (account) {
+    account->GetIncomingServer(getter_AddRefs(server));
+  } else {
+    nsCOMPtr<nsIMsgFolder> folder;
+    aHdr->GetFolder(getter_AddRefs(folder));
+    if (folder) folder->GetServer(getter_AddRefs(server));
+  }
+
+  if (server)
+    server->GetPrettyName(aAccount);
+  else
+    CopyASCIItoUTF16(accountKey, aAccount);
+
+  return NS_OK;
+}
+
+nsresult nsMsgDBView::FetchRecipients(nsIMsgDBHdr* aHdr,
+                                      nsAString& aRecipientsString) {
+  nsCString recipients;
+  int32_t currentDisplayNameVersion = 0;
+  bool showCondensedAddresses = false;
+  nsCOMPtr<nsIPrefBranch> prefs(do_GetService(NS_PREFSERVICE_CONTRACTID));
+
+  prefs->GetIntPref("mail.displayname.version", &currentDisplayNameVersion);
+  prefs->GetBoolPref("mail.showCondensedAddresses", &showCondensedAddresses);
+
+  aHdr->GetStringProperty("recipient_names", recipients);
+
+  if (!recipients.IsEmpty()) {
+    nsCString cachedRecipients;
+    GetCachedName(recipients, currentDisplayNameVersion, cachedRecipients);
+
+    // Recipients have already been cached, check if the addressbook
+    // was changed after cache.
+    if (!cachedRecipients.IsEmpty()) {
+      CopyUTF8toUTF16(cachedRecipients, aRecipientsString);
+      return NS_OK;
+    }
+  }
+
+  nsCString unparsedRecipients;
+  nsresult rv = aHdr->GetRecipients(getter_Copies(unparsedRecipients));
+
+  nsCString headerCharset;
+  aHdr->GetEffectiveCharset(headerCharset);
+
+  nsTArray<nsString> names;
+  nsTArray<nsCString> emails;
+  ExtractAllAddresses(EncodedHeader(unparsedRecipients, headerCharset.get()),
+                      names, UTF16ArrayAdapter<>(emails));
+
+  uint32_t numAddresses = names.Length();
+
+  nsCOMPtr<nsIAbManager> abManager(
+      do_GetService("@mozilla.org/abmanager;1", &rv));
+
+  NS_ENSURE_SUCCESS(rv, NS_OK);
+
+  // Go through each email address in the recipients and compute its
+  // display name.
+  for (uint32_t i = 0; i < numAddresses; i++) {
+    nsString recipient;
+    nsCString& curAddress = emails[i];
+    nsString& curName = names[i];
+
+    if (showCondensedAddresses)
+      GetDisplayNameInAddressBook(curAddress, recipient);
+
+    if (recipient.IsEmpty()) {
+      // We can't use the display name in the card; use the name contained in
+      // the header or email address.
+      if (curName.IsEmpty()) {
+        CopyUTF8toUTF16(curAddress, recipient);
+      } else {
+        int32_t atPos;
+        if ((atPos = curName.FindChar('@')) == kNotFound ||
+            curName.FindChar('.', atPos) == kNotFound) {
+          recipient = curName;
+        } else {
+          // Found @ followed by a dot, so this looks like a spoofing case.
+          recipient = curName;
+          recipient.AppendLiteral(" <");
+          AppendUTF8toUTF16(curAddress, recipient);
+          recipient.Append('>');
+        }
+      }
+    }
+
+    // Add ', ' between each recipient.
+    if (i != 0) aRecipientsString.AppendLiteral(u", ");
+
+    aRecipientsString.Append(recipient);
+  }
+
+  if (numAddresses == 0 && unparsedRecipients.FindChar(':') != kNotFound) {
+    // No addresses and a colon, so an empty group like
+    // "undisclosed-recipients: ;".
+    // Add group name so at least something displays.
+    nsString group;
+    CopyUTF8toUTF16(unparsedRecipients, group);
+    aRecipientsString.Assign(group);
+  }
+
+  UpdateCachedName(aHdr, "recipient_names", aRecipientsString);
+
+  return NS_OK;
+}
+
+nsresult nsMsgDBView::FetchSubject(nsIMsgDBHdr* aMsgHdr, uint32_t aFlags,
+                                   nsAString& aValue) {
+  if (aFlags & nsMsgMessageFlags::HasRe) {
+    nsString subject;
+    aMsgHdr->GetMime2DecodedSubject(subject);
+    aValue.AssignLiteral("Re: ");
+    aValue.Append(subject);
+  } else {
+    aMsgHdr->GetMime2DecodedSubject(aValue);
+  }
+
+  return NS_OK;
+}
+
+// In case we want to play around with the date string, I've broken it out into
+// a separate routine.  Set rcvDate to true to get the Received: date instead
+// of the Date: date.
+nsresult nsMsgDBView::FetchDate(nsIMsgDBHdr* aHdr, nsAString& aDateString,
+                                bool rcvDate) {
+  PRTime dateOfMsg;
+  PRTime dateOfMsgLocal;
+  uint32_t rcvDateSecs;
+  nsresult rv;
+
+  // Silently return Date: instead if Received: is unavailable.
+  if (rcvDate) {
+    rv = aHdr->GetUint32Property("dateReceived", &rcvDateSecs);
+    if (rcvDateSecs != 0) Seconds2PRTime(rcvDateSecs, &dateOfMsg);
+  }
+
+  if (!rcvDate || rcvDateSecs == 0) rv = aHdr->GetDate(&dateOfMsg);
+  NS_ENSURE_SUCCESS(rv, rv);
+
+  PRTime currentTime = PR_Now();
+  PRExplodedTime explodedCurrentTime;
+  PR_ExplodeTime(currentTime, PR_LocalTimeParameters, &explodedCurrentTime);
+  PRExplodedTime explodedMsgTime;
+  PR_ExplodeTime(dateOfMsg, PR_LocalTimeParameters, &explodedMsgTime);
+
+  // If the message is from today, don't show the date, only the time (3:15 pm).
+  // If the message is from the last week, show the day of the week
+  // (Mon 3:15 pm). In all other cases, show the full date (03/19/01 3:15 pm).
+
+  nsDateFormatSelectorComm dateFormat = m_dateFormatDefault;
+  if (explodedCurrentTime.tm_year == explodedMsgTime.tm_year &&
+      explodedCurrentTime.tm_month == explodedMsgTime.tm_month &&
+      explodedCurrentTime.tm_mday == explodedMsgTime.tm_mday) {
+    // Same day.
+    dateFormat = m_dateFormatToday;
+  } else if (currentTime > dateOfMsg) {
+    // The following chunk of code allows us to show a day instead of a number
+    // if the message was received within the last 7 days. i.e. Mon 5:10pm
+    // (depending on the mail.ui.display.dateformat.thisweek pref).
+    // The concrete format used is dependent on a preference setting
+    // (see InitDisplayFormats).
+    // Convert the times from GMT to local time
+    int64_t GMTLocalTimeShift =
+        PR_USEC_PER_SEC * int64_t(explodedCurrentTime.tm_params.tp_gmt_offset +
+                                  explodedCurrentTime.tm_params.tp_dst_offset);
+    currentTime += GMTLocalTimeShift;
+    dateOfMsgLocal = dateOfMsg + GMTLocalTimeShift;
+
+    // Find the most recent midnight.
+    int64_t todaysMicroSeconds = currentTime % PR_USEC_PER_DAY;
+    int64_t mostRecentMidnight = currentTime - todaysMicroSeconds;
+
+    // Most recent midnight minus 6 days.
+    int64_t mostRecentWeek = mostRecentMidnight - (PR_USEC_PER_DAY * 6);
+
+    // Was the message sent during the last week?
+    if (dateOfMsgLocal >= mostRecentWeek) dateFormat = m_dateFormatThisWeek;
+  }
+
+  mozilla::intl::DateTimeFormat::StyleBag style;
+  style.time = mozilla::Some(mozilla::intl::DateTimeFormat::Style::Short);
+  switch (dateFormat) {
+    case kDateFormatNone:
+      rv = mozilla::intl::AppDateTimeFormat::Format(style, dateOfMsg,
+                                                    aDateString);
+      NS_ENSURE_SUCCESS(rv, rv);
+      break;
+    case kDateFormatLong:
+      style.date = mozilla::Some(mozilla::intl::DateTimeFormat::Style::Long);
+      rv = mozilla::intl::AppDateTimeFormat::Format(style, dateOfMsg,
+                                                    aDateString);
+      NS_ENSURE_SUCCESS(rv, rv);
+      break;
+    case kDateFormatShort:
+      style.date = mozilla::Some(mozilla::intl::DateTimeFormat::Style::Short);
+      rv = mozilla::intl::AppDateTimeFormat::Format(style, dateOfMsg,
+                                                    aDateString);
+      NS_ENSURE_SUCCESS(rv, rv);
+      break;
+    case kDateFormatWeekday: {
+      // We want weekday + time.
+      nsAutoString timeString;
+      nsAutoString weekdayString;
+      rv = mozilla::intl::AppDateTimeFormat::Format(style, dateOfMsg,
+                                                    timeString);
+      NS_ENSURE_SUCCESS(rv, rv);
+
+      mozilla::intl::DateTimeFormat::ComponentsBag components{};
+      components.weekday =
+          mozilla::Some(mozilla::intl::DateTimeFormat::Text::Short);
+      rv = mozilla::intl::AppDateTimeFormat::Format(
+          components, &explodedMsgTime, weekdayString);
+      NS_ENSURE_SUCCESS(rv, rv);
+
+      if (nsMsgDBView::m_connectorPattern.IsEmpty()) {
+        nsAutoCString locale;
+        AutoTArray<nsCString, 10> regionalPrefsLocales;
+        mozilla::intl::LocaleService::GetInstance()->GetRegionalPrefsLocales(
+            regionalPrefsLocales);
+        locale.Assign(regionalPrefsLocales[0]);
+        nsAutoCString str;
+        mozilla::intl::OSPreferences::GetInstance()
+            ->GetDateTimeConnectorPattern(locale, str);
+        nsMsgDBView::m_connectorPattern = NS_ConvertUTF8toUTF16(str);
+      }
+
+      nsAutoString pattern(nsMsgDBView::m_connectorPattern);
+      int32_t ind = pattern.Find(u"{1}"_ns);
+      if (ind != kNotFound) {
+        pattern.Replace(ind, 3, weekdayString);
+      }
+      ind = pattern.Find(u"{0}"_ns);
+      if (ind != kNotFound) {
+        pattern.Replace(ind, 3, timeString);
+      }
+      aDateString = pattern;
+      break;
+    }
+
+    default:
+      break;
+  }
+
+  return rv;
+}
+
+nsresult nsMsgDBView::FetchStatus(uint32_t aFlags, nsAString& aStatusString) {
+  if (aFlags & nsMsgMessageFlags::Replied)
+    aStatusString = kRepliedString;
+  else if (aFlags & nsMsgMessageFlags::Forwarded)
+    aStatusString = kForwardedString;
+  else if (aFlags & nsMsgMessageFlags::Redirected)
+    aStatusString = kRedirectedString;
+  else if (aFlags & nsMsgMessageFlags::New)
+    aStatusString = kNewString;
+  else if (aFlags & nsMsgMessageFlags::Read)
+    aStatusString = kReadString;
+
+  return NS_OK;
+}
+
+nsresult nsMsgDBView::FetchSize(nsIMsgDBHdr* aHdr, nsAString& aSizeString) {
+  nsresult rv;
+  nsAutoString formattedSizeString;
+  uint32_t msgSize = 0;
+
+  // For news, show the line count, not the size if the user wants so.
+  if (mShowSizeInLines) {
+    aHdr->GetLineCount(&msgSize);
+    formattedSizeString.AppendInt(msgSize);
+  } else {
+    uint32_t flags = 0;
+
+    aHdr->GetFlags(&flags);
+    if (flags & nsMsgMessageFlags::Partial)
+      aHdr->GetUint32Property("onlineSize", &msgSize);
+
+    if (msgSize == 0) aHdr->GetMessageSize(&msgSize);
+
+    rv = FormatFileSize(msgSize, true, formattedSizeString);
+    NS_ENSURE_SUCCESS(rv, rv);
+  }
+
+  aSizeString = formattedSizeString;
+  // The formattingString Length includes the null terminator byte!
+  if (!formattedSizeString.Last())
+    aSizeString.SetLength(formattedSizeString.Length() - 1);
+
+  return NS_OK;
+}
+
+nsresult nsMsgDBView::FetchPriority(nsIMsgDBHdr* aHdr,
+                                    nsAString& aPriorityString) {
+  nsMsgPriorityValue priority = nsMsgPriority::notSet;
+  aHdr->GetPriority(&priority);
+
+  switch (priority) {
+    case nsMsgPriority::highest:
+      aPriorityString = kHighestPriorityString;
+      break;
+    case nsMsgPriority::high:
+      aPriorityString = kHighPriorityString;
+      break;
+    case nsMsgPriority::low:
+      aPriorityString = kLowPriorityString;
+      break;
+    case nsMsgPriority::lowest:
+      aPriorityString = kLowestPriorityString;
+      break;
+    case nsMsgPriority::normal:
+      aPriorityString = kNormalPriorityString;
+      break;
+    default:
+      break;
+  }
+
+  return NS_OK;
+}
+
+nsresult nsMsgDBView::FetchKeywords(nsIMsgDBHdr* aHdr,
+                                    nsACString& keywordString) {
+  NS_ENSURE_ARG_POINTER(aHdr);
+  nsresult rv = NS_OK;
+  if (!mTagService) {
+    mTagService = do_GetService("@mozilla.org/messenger/tagservice;1", &rv);
+    NS_ENSURE_SUCCESS(rv, rv);
+  }
+  nsCString keywords;
+  aHdr->GetStringProperty("keywords", keywords);
+  keywordString = keywords;
+  return NS_OK;
+}
+
+// If the row is a collapsed thread, we optionally roll-up the keywords in all
+// the messages in the thread, otherwise, return just the keywords for the row.
+nsresult nsMsgDBView::FetchRowKeywords(nsMsgViewIndex aRow, nsIMsgDBHdr* aHdr,
+                                       nsACString& keywordString) {
+  nsresult rv = FetchKeywords(aHdr, keywordString);
+  NS_ENSURE_SUCCESS(rv, rv);
+
+  bool cascadeKeywordsUp = true;
+  nsCOMPtr<nsIPrefBranch> prefs(do_GetService(NS_PREFSERVICE_CONTRACTID));
+  prefs->GetBoolPref("mailnews.display_reply_tag_colors_for_collapsed_threads",
+                     &cascadeKeywordsUp);
+
+  if ((m_viewFlags & nsMsgViewFlagsType::kThreadedDisplay) &&
+      cascadeKeywordsUp) {
+    if ((m_flags[aRow] & MSG_VIEW_FLAG_ISTHREAD) &&
+        (m_flags[aRow] & nsMsgMessageFlags::Elided)) {
+      nsCOMPtr<nsIMsgThread> thread;
+      rv = GetThreadContainingIndex(aRow, getter_AddRefs(thread));
+      if (NS_SUCCEEDED(rv) && thread) {
+        uint32_t numChildren;
+        thread->GetNumChildren(&numChildren);
+        nsCOMPtr<nsIMsgDBHdr> msgHdr;
+        nsCString moreKeywords;
+        for (uint32_t index = 0; index < numChildren; index++) {
+          thread->GetChildHdrAt(index, getter_AddRefs(msgHdr));
+          rv = FetchKeywords(msgHdr, moreKeywords);
+          NS_ENSURE_SUCCESS(rv, rv);
+
+          if (!keywordString.IsEmpty() && !moreKeywords.IsEmpty())
+            keywordString.Append(' ');
+
+          keywordString.Append(moreKeywords);
+        }
+      }
+    }
+  }
+
+  return rv;
+}
+
+nsresult nsMsgDBView::FetchTags(nsIMsgDBHdr* aHdr, nsAString& aTagString) {
+  NS_ENSURE_ARG_POINTER(aHdr);
+  nsresult rv = NS_OK;
+  if (!mTagService) {
+    mTagService = do_GetService("@mozilla.org/messenger/tagservice;1", &rv);
+    NS_ENSURE_SUCCESS(rv, rv);
+  }
+
+  nsString tags;
+  nsCString keywords;
+  aHdr->GetStringProperty("keywords", keywords);
+
+  nsTArray<nsCString> keywordsArray;
+  ParseString(keywords, ' ', keywordsArray);
+  nsAutoString tag;
+
+  for (uint32_t i = 0; i < keywordsArray.Length(); i++) {
+    rv = mTagService->GetTagForKey(keywordsArray[i], tag);
+    if (NS_SUCCEEDED(rv) && !tag.IsEmpty()) {
+      if (!tags.IsEmpty()) tags.Append((char16_t)' ');
+
+      tags.Append(tag);
+    }
+  }
+
+  aTagString = tags;
+  return NS_OK;
+}
+
+/**
+ * Lowercase the email and remove a possible plus addressing part.
+ * E.g. John+test@example.com -> john@example.com.
+ */
+static void ToLowerCaseDropPlusAddessing(nsCString& aEmail) {
+  ToLowerCase(aEmail);
+  int32_t indPlus;
+  if ((indPlus = aEmail.FindChar('+')) == kNotFound) return;
+  int32_t indAt;
+  indAt = aEmail.FindChar('@', indPlus);
+  if (indAt == kNotFound) return;
+  aEmail.ReplaceLiteral(indPlus, indAt - indPlus, "");
+}
+
+bool nsMsgDBView::IsOutgoingMsg(nsIMsgDBHdr* aHdr) {
+  nsString author;
+  aHdr->GetMime2DecodedAuthor(author);
+
+  nsCString emailAddress;
+  nsString name;
+  ExtractFirstAddress(DecodedHeader(author), name, emailAddress);
+  ToLowerCaseDropPlusAddessing(emailAddress);
+  return mEmails.Contains(emailAddress);
+}
+
+// If you call SaveAndClearSelection make sure to call RestoreSelection(),
+// otherwise m_saveRestoreSelectionDepth will be incorrect and will lead to
+// selection msg problems.
+nsresult nsMsgDBView::SaveAndClearSelection(nsMsgKey* aCurrentMsgKey,
+                                            nsTArray<nsMsgKey>& aMsgKeyArray) {
+  // Always return a value in the first parameter.
+  if (aCurrentMsgKey) *aCurrentMsgKey = nsMsgKey_None;
+
+  // We don't do anything on nested Save / Restore calls.
+  m_saveRestoreSelectionDepth++;
+  if (m_saveRestoreSelectionDepth != 1) return NS_OK;
+
+  if (!mTreeSelection) return NS_OK;
+
+  // First, freeze selection.
+  mTreeSelection->SetSelectEventsSuppressed(true);
+
+  // Second, save the current index.
+  if (aCurrentMsgKey) {
+    int32_t currentIndex;
+    if (NS_SUCCEEDED(mTreeSelection->GetCurrentIndex(&currentIndex)) &&
+        currentIndex >= 0 && uint32_t(currentIndex) < GetSize())
+      *aCurrentMsgKey = m_keys[currentIndex];
+    else
+      *aCurrentMsgKey = nsMsgKey_None;
+  }
+
+  // Third, get an array of view indices for the selection.
+  nsMsgViewIndexArray selection;
+  GetIndicesForSelection(selection);
+  int32_t numIndices = selection.Length();
+  aMsgKeyArray.SetLength(numIndices);
+
+  // Now store the msg key for each selected item.
+  nsMsgKey msgKey;
+  for (int32_t index = 0; index < numIndices; index++) {
+    msgKey = m_keys[selection[index]];
+    aMsgKeyArray[index] = msgKey;
+  }
+
+  // Clear the selection, we'll manually restore it later.
+  if (mTreeSelection) mTreeSelection->ClearSelection();
+
+  return NS_OK;
+}
+
+nsresult nsMsgDBView::RestoreSelection(nsMsgKey aCurrentMsgKey,
+                                       nsTArray<nsMsgKey>& aMsgKeyArray) {
+  // We don't do anything on nested Save / Restore calls.
+  m_saveRestoreSelectionDepth--;
+  if (m_saveRestoreSelectionDepth) return NS_OK;
+
+  // Don't assert.
+  if (!mTreeSelection) return NS_OK;
+
+  // Turn our message keys into corresponding view indices.
+  int32_t arraySize = aMsgKeyArray.Length();
+  nsMsgViewIndex currentViewPosition = nsMsgViewIndex_None;
+  nsMsgViewIndex newViewPosition = nsMsgViewIndex_None;
+
+  // If we are threaded, we need to do a little more work
+  // we need to find (and expand) all the threads that contain messages
+  // that we had selected before.
+  if (m_viewFlags & nsMsgViewFlagsType::kThreadedDisplay) {
+    for (int32_t index = 0; index < arraySize; index++)
+      FindKey(aMsgKeyArray[index], true /* expand */);
+  }
+
+  for (int32_t index = 0; index < arraySize; index++) {
+    newViewPosition = FindKey(aMsgKeyArray[index], false);
+    // Add the index back to the selection.
+    if (newViewPosition != nsMsgViewIndex_None)
+      mTreeSelection->ToggleSelect(newViewPosition);
+  }
+
+  // Make sure the currentView was preserved.
+  if (aCurrentMsgKey != nsMsgKey_None)
+    currentViewPosition = FindKey(aCurrentMsgKey, true);
+
+  if (mJSTree) mJSTree->SetCurrentIndex(currentViewPosition);
+
+  // Make sure the current message is once again visible in the thread pane
+  // so we don't have to go search for it in the thread pane
+  if (currentViewPosition != nsMsgViewIndex_None) {
+    if (mJSTree) {
+      mJSTree->EnsureRowIsVisible(currentViewPosition);
+    } else if (mTree) {
+      mTree->EnsureRowIsVisible(currentViewPosition);
+    }
+  }
+
+  // Unfreeze selection.
+  mTreeSelection->SetSelectEventsSuppressed(false);
+  return NS_OK;
+}
+
+nsresult nsMsgDBView::GenerateURIForMsgKey(nsMsgKey aMsgKey,
+                                           nsIMsgFolder* folder,
+                                           nsACString& aURI) {
+  NS_ENSURE_ARG(folder);
+  return folder->GenerateMessageURI(aMsgKey, aURI);
+}
+
+nsresult nsMsgDBView::GetMessageEnumerator(nsIMsgEnumerator** enumerator) {
+  return m_db->EnumerateMessages(enumerator);
+}
+
+NS_IMETHODIMP
+nsMsgDBView::IsEditable(int32_t row, nsTreeColumn* col, bool* _retval) {
+  NS_ENSURE_ARG_POINTER(col);
+  NS_ENSURE_ARG_POINTER(_retval);
+  // Attempt to retrieve a custom column handler. If it exists call it and
+  // return.
+  const nsAString& colID = col->GetId();
+  nsIMsgCustomColumnHandler* colHandler = GetColumnHandler(colID);
+
+  if (colHandler) {
+    colHandler->IsEditable(row, col, _retval);
+    return NS_OK;
+  }
+
+  *_retval = false;
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsMsgDBView::SetCellValue(int32_t row, nsTreeColumn* col,
+                          const nsAString& value) {
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsMsgDBView::SetCellText(int32_t row, nsTreeColumn* col,
+                         const nsAString& value) {
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsMsgDBView::GetRowCount(int32_t* aRowCount) {
+  *aRowCount = GetSize();
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsMsgDBView::GetSelection(nsITreeSelection** aSelection) {
+  NS_IF_ADDREF(*aSelection = mTreeSelection);
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsMsgDBView::SetSelection(nsITreeSelection* aSelection) {
+  mTreeSelection = aSelection;
+  return NS_OK;
+}
+
+nsresult nsMsgDBView::UpdateDisplayMessage(nsMsgViewIndex viewPosition) {
+  nsCOMPtr<nsIMsgDBViewCommandUpdater> commandUpdater(
+      do_QueryReferent(mCommandUpdater));
+  if (!commandUpdater) return NS_OK;
+
+  if (!IsValidIndex(viewPosition)) return NS_MSG_INVALID_DBVIEW_INDEX;
+
+  // Get the subject and the folder for the message and inform the front
+  // end that we changed the message we are currently displaying.
+  nsresult rv;
+  nsCOMPtr<nsIMsgDBHdr> msgHdr;
+  rv = GetMsgHdrForViewIndex(viewPosition, getter_AddRefs(msgHdr));
+  NS_ENSURE_SUCCESS(rv, rv);
+
+  nsString subject;
+  if (viewPosition >= (nsMsgViewIndex)m_flags.Length())
+    return NS_MSG_INVALID_DBVIEW_INDEX;
+  FetchSubject(msgHdr, m_flags[viewPosition], subject);
+
+  nsCString keywords;
+  rv = msgHdr->GetStringProperty("keywords", keywords);
+  NS_ENSURE_SUCCESS(rv, rv);
+
+  nsCOMPtr<nsIMsgFolder> folder = m_viewFolder ? m_viewFolder : m_folder;
+
+  commandUpdater->DisplayMessageChanged(folder, subject, keywords);
+
+  if (folder) {
+    if (viewPosition >= (nsMsgViewIndex)m_keys.Length())
+      return NS_MSG_INVALID_DBVIEW_INDEX;
+    rv = folder->SetLastMessageLoaded(m_keys[viewPosition]);
+    NS_ENSURE_SUCCESS(rv, rv);
+  }
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsMsgDBView::SelectionChangedXPCOM() {
+  // If the currentSelection changed then we have a message to display -
+  // not if we are in the middle of deleting rows.
+  if (m_deletingRows) return NS_OK;
+
+  nsMsgViewIndexArray selection;
+  GetIndicesForSelection(selection);
+
+  bool commandsNeedDisablingBecauseOfSelection = false;
+
+  if (!selection.IsEmpty()) {
+    if (WeAreOffline())
+      commandsNeedDisablingBecauseOfSelection = !OfflineMsgSelected(selection);
+
+    if (!NonDummyMsgSelected(selection))
+      commandsNeedDisablingBecauseOfSelection = true;
+  }
+
+  bool selectionSummarized = false;
+  mSummarizeFailed = false;
+  // Let the front-end adjust the message pane appropriately with either
+  // the message body, or a summary of the selection.
+  nsCOMPtr<nsIMsgDBViewCommandUpdater> commandUpdater(
+      do_QueryReferent(mCommandUpdater));
+  if (commandUpdater) {
+    commandUpdater->SummarizeSelection(&selectionSummarized);
+    // Check if the selection was not summarized, but we expected it to be,
+    // and if so, remember it so GetHeadersFromSelection won't include
+    // the messages in collapsed threads.
+    if (!selectionSummarized &&
+        (selection.Length() > 1 ||
+         (selection.Length() == 1 &&
+          m_flags[selection[0]] & nsMsgMessageFlags::Elided &&
+          OperateOnMsgsInCollapsedThreads()))) {
+      mSummarizeFailed = true;
+    }
+  }
+
+  bool summaryStateChanged = selectionSummarized != mSelectionSummarized;
+  mSelectionSummarized = selectionSummarized;
+
+  if (!mTreeSelection || selection.Length() != 1 || selectionSummarized) {
+    // If we have zero or multiple items selected, we shouldn't be displaying
+    // any message.
+    m_currentlyDisplayedMsgKey = nsMsgKey_None;
+    m_currentlyDisplayedMsgUri.Truncate();
+    m_currentlyDisplayedViewIndex = nsMsgViewIndex_None;
+  }
+
+  // Determine if we need to push command update notifications out to the UI.
+  // We need to push a command update notification iff, one of the following
+  // conditions are met
+  // (1) the selection went from 0 to 1
+  // (2) it went from 1 to 0
+  // (3) it went from 1 to many
+  // (4) it went from many to 1 or 0
+  // (5) a different msg was selected - perhaps it was offline or not,
+  //     matters only when we are offline
+  // (6) we did a forward/back, or went from having no history to having
+  //     history - not sure how to tell this.
+  // (7) whether the selection was summarized or not changed.
+
+  // I think we're going to need to keep track of whether forward/back were
+  // enabled/should be enabled, and when this changes, force a command update.
+
+  if (!summaryStateChanged &&
+      (selection.Length() == mNumSelectedRows ||
+       (selection.Length() > 1 && mNumSelectedRows > 1)) &&
+      commandsNeedDisablingBecauseOfSelection ==
+          mCommandsNeedDisablingBecauseOfSelection) {
+    // Don't update commands if we're suppressing them, or if we're removing
+    // rows, unless it was the last row.
+  } else if (!mSuppressCommandUpdating && commandUpdater &&
+             (!mRemovingRow || GetSize() == 0)) {
+    commandUpdater->UpdateCommandStatus();
+  }
+
+  mCommandsNeedDisablingBecauseOfSelection =
+      commandsNeedDisablingBecauseOfSelection;
+  mNumSelectedRows = selection.Length();
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsMsgDBView::GetRowProperties(int32_t index, nsAString& properties) {
+  if (!IsValidIndex(index)) return NS_MSG_INVALID_DBVIEW_INDEX;
+
+  // This is where we tell the tree to apply styles to a particular row.
+  nsCOMPtr<nsIMsgDBHdr> msgHdr;
+  nsresult rv = NS_OK;
+
+  rv = GetMsgHdrForViewIndex(index, getter_AddRefs(msgHdr));
+
+  if (NS_FAILED(rv) || !msgHdr) {
+    ClearHdrCache();
+    return NS_MSG_INVALID_DBVIEW_INDEX;
+  }
+
+  if (IsOutgoingMsg(msgHdr)) properties.AppendLiteral(" outgoing");
+
+  nsCString keywordProperty;
+  FetchRowKeywords(index, msgHdr, keywordProperty);
+  bool tagAdded = false;
+  if (!keywordProperty.IsEmpty()) {
+    AppendKeywordProperties(keywordProperty, properties, &tagAdded);
+  }
+  if (tagAdded) {
+    properties.AppendLiteral(" tagged");
+  } else {
+    properties.AppendLiteral(" untagged");
+  }
+
+  uint32_t flags;
+  msgHdr->GetFlags(&flags);
+
+  if (!(flags & nsMsgMessageFlags::Read))
+    properties.AppendLiteral(" unread");
+  else
+    properties.AppendLiteral(" read");
+
+  if (flags & nsMsgMessageFlags::Replied) properties.AppendLiteral(" replied");
+
+  if (flags & nsMsgMessageFlags::Forwarded)
+    properties.AppendLiteral(" forwarded");
+
+  if (flags & nsMsgMessageFlags::Redirected)
+    properties.AppendLiteral(" redirected");
+
+  if (flags & nsMsgMessageFlags::New) properties.AppendLiteral(" new");
+
+  if (m_flags[index] & nsMsgMessageFlags::Marked)
+    properties.AppendLiteral(" flagged");
+
+  // Give the custom column handlers a chance to style the row.
+  for (int i = 0; i < m_customColumnHandlers.Count(); i++) {
+    nsString extra;
+    m_customColumnHandlers[i]->GetRowProperties(index, extra);
+    if (!extra.IsEmpty()) {
+      properties.Append(' ');
+      properties.Append(extra);
+    }
+  }
+
+  // For threaded display add the ignoreSubthread property to the
+  // subthread top row (this row). For non-threaded add it to all rows.
+  if (!(m_viewFlags & nsMsgViewFlagsType::kThreadedDisplay) &&
+      (flags & nsMsgMessageFlags::Ignored)) {
+    properties.AppendLiteral(" ignoreSubthread");
+  } else {
+    bool ignored;
+    msgHdr->GetIsKilled(&ignored);
+    if (ignored) properties.AppendLiteral(" ignoreSubthread");
+  }
+
+  nsCOMPtr<nsIMsgLocalMailFolder> localFolder = do_QueryInterface(m_folder);
+
+  if ((flags & nsMsgMessageFlags::Offline) ||
+      (localFolder && !(flags & nsMsgMessageFlags::Partial)))
+    properties.AppendLiteral(" offline");
+
+  if (flags & nsMsgMessageFlags::Attachment)
+    properties.AppendLiteral(" attach");
+
+  if ((mDeleteModel == nsMsgImapDeleteModels::IMAPDelete) &&
+      (flags & nsMsgMessageFlags::IMAPDeleted))
+    properties.AppendLiteral(" imapdeleted");
+
+  nsCString imageSize;
+  msgHdr->GetStringProperty("imageSize", imageSize);
+  if (!imageSize.IsEmpty()) properties.AppendLiteral(" hasimage");
+
+  nsCString junkScoreStr;
+  msgHdr->GetStringProperty("junkscore", junkScoreStr);
+  if (!junkScoreStr.IsEmpty()) {
+    if (junkScoreStr.ToInteger(&rv) == nsIJunkMailPlugin::IS_SPAM_SCORE)
+      properties.AppendLiteral(" junk");
+    else
+      properties.AppendLiteral(" notjunk");
+
+    NS_ASSERTION(NS_SUCCEEDED(rv), "Converting junkScore to integer failed.");
+  }
+
+  nsCOMPtr<nsIMsgThread> thread;
+  rv = GetThreadContainingIndex(index, getter_AddRefs(thread));
+  if (NS_SUCCEEDED(rv) && thread) {
+    uint32_t numUnreadChildren;
+    thread->GetNumUnreadChildren(&numUnreadChildren);
+    if (numUnreadChildren > 0) properties.AppendLiteral(" hasUnread");
+
+    // For threaded display add the ignore/watch properties to the
+    // thread top row. For non-threaded add it to all rows.
+    if (!(m_viewFlags & nsMsgViewFlagsType::kThreadedDisplay) ||
+        ((m_viewFlags & nsMsgViewFlagsType::kThreadedDisplay) &&
+         (m_flags[index] & MSG_VIEW_FLAG_ISTHREAD))) {
+      thread->GetFlags(&flags);
+      if (flags & nsMsgMessageFlags::Watched)
+        properties.AppendLiteral(" watch");
+      if (flags & nsMsgMessageFlags::Ignored)
+        properties.AppendLiteral(" ignore");
+    }
+  }
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsMsgDBView::GetColumnProperties(nsTreeColumn* col, nsAString& properties) {
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsMsgDBView::GetCellProperties(int32_t aRow, nsTreeColumn* col,
+                               nsAString& properties) {
+  if (!IsValidIndex(aRow)) return NS_MSG_INVALID_DBVIEW_INDEX;
+
+  // This is where we tell the tree to apply styles to a particular row
+  // i.e. if the row is an unread message...
+
+  nsCOMPtr<nsIMsgDBHdr> msgHdr;
+  nsresult rv = NS_OK;
+
+  rv = GetMsgHdrForViewIndex(aRow, getter_AddRefs(msgHdr));
+
+  if (NS_FAILED(rv) || !msgHdr) {
+    ClearHdrCache();
+    return NS_MSG_INVALID_DBVIEW_INDEX;
+  }
+
+  const nsAString& colID = col->GetId();
+  nsIMsgCustomColumnHandler* colHandler = GetColumnHandler(colID);
+  if (colHandler != nullptr) {
+    colHandler->GetCellProperties(aRow, col, properties);
+  } else if (colID[0] == 'c') {
+    // Correspondent.
+    if (IsOutgoingMsg(msgHdr))
+      properties.AssignLiteral("outgoing");
+    else
+      properties.AssignLiteral("incoming");
+  }
+
+  if (!properties.IsEmpty()) properties.Append(' ');
+
+  properties.Append(mMessageType);
+
+  uint32_t flags;
+  msgHdr->GetFlags(&flags);
+
+  if (!(flags & nsMsgMessageFlags::Read))
+    properties.AppendLiteral(" unread");
+  else
+    properties.AppendLiteral(" read");
+
+  if (flags & nsMsgMessageFlags::Replied) properties.AppendLiteral(" replied");
+
+  if (flags & nsMsgMessageFlags::Forwarded)
+    properties.AppendLiteral(" forwarded");
+
+  if (flags & nsMsgMessageFlags::Redirected)
+    properties.AppendLiteral(" redirected");
+
+  if (flags & nsMsgMessageFlags::New) properties.AppendLiteral(" new");
+
+  if (m_flags[aRow] & nsMsgMessageFlags::Marked)
+    properties.AppendLiteral(" flagged");
+
+  // For threaded display add the ignoreSubthread property to the
+  // subthread top row (this row). For non-threaded add it to all rows.
+  if (!(m_viewFlags & nsMsgViewFlagsType::kThreadedDisplay) &&
+      (flags & nsMsgMessageFlags::Ignored)) {
+    properties.AppendLiteral(" ignoreSubthread");
+  } else {
+    bool ignored;
+    msgHdr->GetIsKilled(&ignored);
+    if (ignored) properties.AppendLiteral(" ignoreSubthread");
+  }
+
+  nsCOMPtr<nsIMsgLocalMailFolder> localFolder = do_QueryInterface(m_folder);
+
+  if ((flags & nsMsgMessageFlags::Offline) ||
+      (localFolder && !(flags & nsMsgMessageFlags::Partial)))
+    properties.AppendLiteral(" offline");
+
+  if (flags & nsMsgMessageFlags::Attachment)
+    properties.AppendLiteral(" attach");
+
+  if ((mDeleteModel == nsMsgImapDeleteModels::IMAPDelete) &&
+      (flags & nsMsgMessageFlags::IMAPDeleted))
+    properties.AppendLiteral(" imapdeleted");
+
+  nsCString imageSize;
+  msgHdr->GetStringProperty("imageSize", imageSize);
+  if (!imageSize.IsEmpty()) properties.AppendLiteral(" hasimage");
+
+  nsCString junkScoreStr;
+  msgHdr->GetStringProperty("junkscore", junkScoreStr);
+  if (!junkScoreStr.IsEmpty()) {
+    if (junkScoreStr.ToInteger(&rv) == nsIJunkMailPlugin::IS_SPAM_SCORE)
+      properties.AppendLiteral(" junk");
+    else
+      properties.AppendLiteral(" notjunk");
+
+    NS_ASSERTION(NS_SUCCEEDED(rv), "Converting junkScore to integer failed.");
+  }
+
+  nsCString keywords;
+  FetchRowKeywords(aRow, msgHdr, keywords);
+  bool tagAdded = false;
+  if (!keywords.IsEmpty()) {
+    AppendKeywordProperties(keywords, properties, &tagAdded);
+  }
+  if (tagAdded) {
+    properties.AppendLiteral(" tagged");
+  } else {
+    properties.AppendLiteral(" untagged");
+  }
+
+  // This is a double fetch of the keywords property since we also fetch
+  // it for the tags - do we want to do this?
+  // I'm not sure anyone uses the kw- property, though it could be nice
+  // for people wanting to extend the thread pane.
+  nsCString keywordProperty;
+  msgHdr->GetStringProperty("keywords", keywordProperty);
+  if (!keywordProperty.IsEmpty()) {
+    NS_ConvertUTF8toUTF16 keywords(keywordProperty);
+    int32_t spaceIndex = 0;
+    do {
+      spaceIndex = keywords.FindChar(' ');
+      int32_t endOfKeyword =
+          (spaceIndex == -1) ? keywords.Length() : spaceIndex;
+      properties.AppendLiteral(" kw-");
+      properties.Append(StringHead(keywords, endOfKeyword));
+      if (spaceIndex > 0) keywords.Cut(0, endOfKeyword + 1);
+    } while (spaceIndex > 0);
+  }
+
+#ifdef SUPPORT_PRIORITY_COLORS
+  // Add special styles for priority.
+  nsMsgPriorityValue priority;
+  msgHdr->GetPriority(&priority);
+  switch (priority) {
+    case nsMsgPriority::highest:
+      properties.append(" priority-highest");
+      break;
+    case nsMsgPriority::high:
+      properties.append(" priority-high");
+      break;
+    case nsMsgPriority::low:
+      properties.append(" priority-low");
+      break;
+    case nsMsgPriority::lowest:
+      properties.append(" priority-lowest");
+      break;
+    default:
+      break;
+  }
+#endif
+
+  nsCOMPtr<nsIMsgThread> thread;
+  rv = GetThreadContainingIndex(aRow, getter_AddRefs(thread));
+  if (NS_SUCCEEDED(rv) && thread) {
+    uint32_t numUnreadChildren;
+    thread->GetNumUnreadChildren(&numUnreadChildren);
+    if (numUnreadChildren > 0) properties.AppendLiteral(" hasUnread");
+
+    // For threaded display add the ignore/watch properties to the
+    // thread top row. For non-threaded add it to all rows.
+    if (!(m_viewFlags & nsMsgViewFlagsType::kThreadedDisplay) ||
+        ((m_viewFlags & nsMsgViewFlagsType::kThreadedDisplay) &&
+         (m_flags[aRow] & MSG_VIEW_FLAG_ISTHREAD))) {
+      thread->GetFlags(&flags);
+      if (flags & nsMsgMessageFlags::Watched)
+        properties.AppendLiteral(" watch");
+      if (flags & nsMsgMessageFlags::Ignored)
+        properties.AppendLiteral(" ignore");
+    }
+  }
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsMsgDBView::IsContainer(int32_t index, bool* _retval) {
+  if (!IsValidIndex(index)) return NS_MSG_INVALID_DBVIEW_INDEX;
+
+  if (m_viewFlags & nsMsgViewFlagsType::kThreadedDisplay) {
+    uint32_t flags = m_flags[index];
+    *_retval = !!(flags & MSG_VIEW_FLAG_HASCHILDREN);
+  } else {
+    *_retval = false;
+  }
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsMsgDBView::IsContainerOpen(int32_t index, bool* _retval) {
+  if (!IsValidIndex(index)) return NS_MSG_INVALID_DBVIEW_INDEX;
+
+  if (m_viewFlags & nsMsgViewFlagsType::kThreadedDisplay) {
+    uint32_t flags = m_flags[index];
+    *_retval = (flags & MSG_VIEW_FLAG_HASCHILDREN) &&
+               !(flags & nsMsgMessageFlags::Elided);
+  } else {
+    *_retval = false;
+  }
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsMsgDBView::IsContainerEmpty(int32_t index, bool* _retval) {
+  if (!IsValidIndex(index)) return NS_MSG_INVALID_DBVIEW_INDEX;
+
+  if (m_viewFlags & nsMsgViewFlagsType::kThreadedDisplay) {
+    uint32_t flags = m_flags[index];
+    *_retval = !(flags & MSG_VIEW_FLAG_HASCHILDREN);
+  } else {
+    *_retval = false;
+  }
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsMsgDBView::IsSeparator(int32_t index, bool* _retval) {
+  if (!IsValidIndex(index)) return NS_MSG_INVALID_DBVIEW_INDEX;
+
+  *_retval = false;
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsMsgDBView::GetParentIndex(int32_t rowIndex, int32_t* _retval) {
+  *_retval = -1;
+
+  int32_t rowIndexLevel;
+  nsresult rv = GetLevel(rowIndex, &rowIndexLevel);
+  NS_ENSURE_SUCCESS(rv, rv);
+
+  int32_t i;
+  for (i = rowIndex; i >= 0; i--) {
+    int32_t l;
+    GetLevel(i, &l);
+    if (l < rowIndexLevel) {
+      *_retval = i;
+      break;
+    }
+  }
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsMsgDBView::HasNextSibling(int32_t rowIndex, int32_t afterIndex,
+                            bool* _retval) {
+  *_retval = false;
+
+  int32_t rowIndexLevel;
+  GetLevel(rowIndex, &rowIndexLevel);
+
+  int32_t i;
+  int32_t count;
+  GetRowCount(&count);
+  for (i = afterIndex + 1; i < count; i++) {
+    int32_t l;
+    GetLevel(i, &l);
+    if (l < rowIndexLevel) break;
+
+    if (l == rowIndexLevel) {
+      *_retval = true;
+      break;
+    }
+  }
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsMsgDBView::GetLevel(int32_t index, int32_t* _retval) {
+  if (!IsValidIndex(index)) return NS_MSG_INVALID_DBVIEW_INDEX;
+
+  if (m_viewFlags & nsMsgViewFlagsType::kThreadedDisplay)
+    *_retval = m_levels[index];
+  else
+    *_retval = 0;
+
+  return NS_OK;
+}
+
+// Search view will override this since headers can span db's.
+nsresult nsMsgDBView::GetMsgHdrForViewIndex(nsMsgViewIndex index,
+                                            nsIMsgDBHdr** msgHdr) {
+  nsresult rv = NS_OK;
+  if (!IsValidIndex(index)) return NS_MSG_INVALID_DBVIEW_INDEX;
+
+  nsMsgKey key = m_keys[index];
+  if (key == nsMsgKey_None || !m_db) return NS_MSG_INVALID_DBVIEW_INDEX;
+
+  if (key == m_cachedMsgKey) {
+    NS_IF_ADDREF(*msgHdr = m_cachedHdr);
+  } else {
+    rv = m_db->GetMsgHdrForKey(key, msgHdr);
+    if (NS_SUCCEEDED(rv)) {
+      m_cachedHdr = *msgHdr;
+      m_cachedMsgKey = key;
+    }
+  }
+
+  return rv;
+}
+
+void nsMsgDBView::InsertMsgHdrAt(nsMsgViewIndex index, nsIMsgDBHdr* hdr,
+                                 nsMsgKey msgKey, uint32_t flags,
+                                 uint32_t level) {
+  if ((int32_t)index < 0 || index > m_keys.Length()) {
+    // Something's gone wrong in a caller, but we have no clue why.
+    // Return without adding the header to the view.
+    NS_ERROR("Index for message header insertion out of array range!");
+    return;
+  }
+
+  m_keys.InsertElementAt(index, msgKey);
+  m_flags.InsertElementAt(index, flags);
+  m_levels.InsertElementAt(index, level);
+}
+
+void nsMsgDBView::SetMsgHdrAt(nsIMsgDBHdr* hdr, nsMsgViewIndex index,
+                              nsMsgKey msgKey, uint32_t flags, uint32_t level) {
+  m_keys[index] = msgKey;
+  m_flags[index] = flags;
+  m_levels[index] = level;
+}
+
+nsresult nsMsgDBView::GetFolderForViewIndex(nsMsgViewIndex index,
+                                            nsIMsgFolder** aFolder) {
+  NS_IF_ADDREF(*aFolder = m_folder);
+  return NS_OK;
+}
+
+nsresult nsMsgDBView::GetDBForViewIndex(nsMsgViewIndex index,
+                                        nsIMsgDatabase** db) {
+  NS_IF_ADDREF(*db = m_db);
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsMsgDBView::GetImageSrc(int32_t aRow, nsTreeColumn* aCol, nsAString& aValue) {
+  NS_ENSURE_ARG_POINTER(aCol);
+  // Attempt to retrieve a custom column handler. If it exists call it and
+  // return.
+  const nsAString& colID = aCol->GetId();
+  nsIMsgCustomColumnHandler* colHandler = GetColumnHandler(colID);
+
+  if (colHandler) {
+    colHandler->GetImageSrc(aRow, aCol, aValue);
+    return NS_OK;
+  }
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsMsgDBView::GetCellValue(int32_t aRow, nsTreeColumn* aCol, nsAString& aValue) {
+  if (!IsValidIndex(aRow)) return NS_MSG_INVALID_DBVIEW_INDEX;
+
+  nsCOMPtr<nsIMsgDBHdr> msgHdr;
+  nsresult rv = GetMsgHdrForViewIndex(aRow, getter_AddRefs(msgHdr));
+
+  if (NS_FAILED(rv) || !msgHdr) {
+    ClearHdrCache();
+    return NS_MSG_INVALID_DBVIEW_INDEX;
+  }
+
+  const nsAString& colID = aCol->GetId();
+
+  aValue.Truncate();
+  if (colID.IsEmpty()) return NS_OK;
+
+  uint32_t flags;
+  msgHdr->GetFlags(&flags);
+
+  // Provide a string "value" for cells that do not normally have text.
+  // Use empty string for the normal states "Read", "Not Starred",
+  // "No Attachment" and "Not Junk".
+  switch (colID.First()) {
+    case 'a':
+      if (colID.EqualsLiteral("attachmentCol") &&
+          flags & nsMsgMessageFlags::Attachment) {
+        GetString(u"messageHasAttachment", aValue);
+      }
+      break;
+    case 'f':
+      if (colID.EqualsLiteral("flaggedCol") &&
+          flags & nsMsgMessageFlags::Marked) {
+        GetString(u"messageHasFlag", aValue);
+      }
+      break;
+    case 'j':
+      if (colID.EqualsLiteral("junkStatusCol") && JunkControlsEnabled(aRow)) {
+        nsCString junkScoreStr;
+        msgHdr->GetStringProperty("junkscore", junkScoreStr);
+        // Only need to assign a real value for junk, it's empty already
+        // as it should be for non-junk.
+        if (!junkScoreStr.IsEmpty() &&
+            (junkScoreStr.ToInteger(&rv) == nsIJunkMailPlugin::IS_SPAM_SCORE))
+          aValue.AssignLiteral("messageJunk");
+
+        NS_ASSERTION(NS_SUCCEEDED(rv),
+                     "Converting junkScore to integer failed.");
+      }
+      break;
+    case 't':
+      if (colID.EqualsLiteral("threadCol") &&
+          (m_viewFlags & nsMsgViewFlagsType::kThreadedDisplay)) {
+        // thread column
+        bool isContainer, isContainerEmpty, isContainerOpen;
+        IsContainer(aRow, &isContainer);
+        if (isContainer) {
+          IsContainerEmpty(aRow, &isContainerEmpty);
+          if (!isContainerEmpty) {
+            IsContainerOpen(aRow, &isContainerOpen);
+            GetString(
+                isContainerOpen ? u"messageExpanded" : u"messageCollapsed",
+                aValue);
+          }
+        }
+      }
+      break;
+    case 'u':
+      if (colID.EqualsLiteral("unreadButtonColHeader") &&
+          !(flags & nsMsgMessageFlags::Read)) {
+        GetString(u"messageUnread", aValue);
+      }
+      break;
+    default:
+      aValue.Assign(colID);
+      break;
+  }
+
+  return rv;
+}
+
+void nsMsgDBView::RememberDeletedMsgHdr(nsIMsgDBHdr* msgHdr) {
+  nsCString messageId;
+  msgHdr->GetMessageId(getter_Copies(messageId));
+  if (mRecentlyDeletedArrayIndex >= mRecentlyDeletedMsgIds.Length())
+    mRecentlyDeletedMsgIds.AppendElement(messageId);
+  else
+    mRecentlyDeletedMsgIds[mRecentlyDeletedArrayIndex] = messageId;
+
+  // Only remember last 20 deleted msgs.
+  mRecentlyDeletedArrayIndex = (mRecentlyDeletedArrayIndex + 1) % 20;
+}
+
+bool nsMsgDBView::WasHdrRecentlyDeleted(nsIMsgDBHdr* msgHdr) {
+  nsCString messageId;
+  msgHdr->GetMessageId(getter_Copies(messageId));
+  return mRecentlyDeletedMsgIds.Contains(messageId);
+}
+
+/**
+ * CUSTOM COLUMNS.
+ */
+
+// Add a custom column handler.
+NS_IMETHODIMP
+nsMsgDBView::AddColumnHandler(const nsAString& column,
+                              nsIMsgCustomColumnHandler* handler) {
+  bool custColInSort = false;
+  size_t index = m_customColumnHandlerIDs.IndexOf(column);
+
+  nsAutoString strColID(column);
+
+  // Does not exist.
+  if (index == m_customColumnHandlerIDs.NoIndex) {
+    m_customColumnHandlerIDs.AppendElement(strColID);
+    m_customColumnHandlers.AppendObject(handler);
+  } else {
+    // Insert new handler into the appropriate place in the COMPtr array;
+    // no need to replace the column ID (it's the same).
+    m_customColumnHandlers.ReplaceObjectAt(handler, index);
+  }
+
+  // Check if the column name matches any of the columns in
+  // m_sortColumns, and if so, set m_sortColumns[i].mColHandler
+  for (uint32_t i = 0; i < m_sortColumns.Length(); i++) {
+    MsgViewSortColumnInfo& sortInfo = m_sortColumns[i];
+    if (sortInfo.mSortType == nsMsgViewSortType::byCustom &&
+        sortInfo.mCustomColumnName.Equals(column)) {
+      custColInSort = true;
+      sortInfo.mColHandler = handler;
+    }
+  }
+
+  if (m_viewFlags & nsMsgViewFlagsType::kGroupBySort)
+    // Grouped view has its own ways.
+    return NS_OK;
+
+  // This cust col is in sort columns, and all are now registered, so sort.
+  if (custColInSort && !CustomColumnsInSortAndNotRegistered())
+    Sort(m_sortType, m_sortOrder);
+
+  return NS_OK;
+}
+
+// Remove a custom column handler.
+NS_IMETHODIMP
+nsMsgDBView::RemoveColumnHandler(const nsAString& aColID) {
+  // Here we should check if the column name matches any of the columns in
+  // m_sortColumns, and if so, clear m_sortColumns[i].mColHandler.
+  size_t index = m_customColumnHandlerIDs.IndexOf(aColID);
+
+  if (index != m_customColumnHandlerIDs.NoIndex) {
+    m_customColumnHandlerIDs.RemoveElementAt(index);
+    m_customColumnHandlers.RemoveObjectAt(index);
+    // Check if the column name matches any of the columns in
+    // m_sortColumns, and if so, clear m_sortColumns[i].mColHandler.
+    for (uint32_t i = 0; i < m_sortColumns.Length(); i++) {
+      MsgViewSortColumnInfo& sortInfo = m_sortColumns[i];
+      if (sortInfo.mSortType == nsMsgViewSortType::byCustom &&
+          sortInfo.mCustomColumnName.Equals(aColID))
+        sortInfo.mColHandler = nullptr;
+    }
+
+    return NS_OK;
+  }
+
+  // Can't remove a column that isn't currently custom handled.
+  return NS_ERROR_FAILURE;
+}
+
+// TODO: NS_ENSURE_SUCCESS
+nsIMsgCustomColumnHandler* nsMsgDBView::GetCurColumnHandler() {
+  return GetColumnHandler(m_curCustomColumn);
+}
+
+NS_IMETHODIMP
+nsMsgDBView::SetCurCustomColumn(const nsAString& aColID) {
+  m_curCustomColumn = aColID;
+  if (m_viewFolder) {
+    nsCOMPtr<nsIMsgDatabase> db;
+    nsCOMPtr<nsIDBFolderInfo> folderInfo;
+    nsresult rv = m_viewFolder->GetDBFolderInfoAndDB(getter_AddRefs(folderInfo),
+                                                     getter_AddRefs(db));
+    NS_ENSURE_SUCCESS(rv, rv);
+    folderInfo->SetProperty("customSortCol", aColID);
+  }
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsMsgDBView::GetCurCustomColumn(nsAString& result) {
+  result = m_curCustomColumn;
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsMsgDBView::GetSecondaryCustomColumn(nsAString& result) {
+  result = m_secondaryCustomColumn;
+  return NS_OK;
+}
+
+nsIMsgCustomColumnHandler* nsMsgDBView::GetColumnHandler(
+    const nsAString& colID) {
+  size_t index = m_customColumnHandlerIDs.IndexOf(colID);
+  return (index != m_customColumnHandlerIDs.NoIndex)
+             ? m_customColumnHandlers[index]
+             : nullptr;
+}
+
+NS_IMETHODIMP
+nsMsgDBView::GetColumnHandler(const nsAString& aColID,
+                              nsIMsgCustomColumnHandler** aHandler) {
+  NS_ENSURE_ARG_POINTER(aHandler);
+  nsAutoString column(aColID);
+  NS_IF_ADDREF(*aHandler = GetColumnHandler(column));
+  return (*aHandler) ? NS_OK : NS_ERROR_FAILURE;
+}
+
+// Check if any active sort columns are custom. If none are custom, return false
+// and go on as always. If any are custom, and all are not registered yet,
+// return true (so that the caller can postpone sort). When the custom column
+// observer is notified with MsgCreateDBView and registers the handler,
+// AddColumnHandler will sort once all required handlers are set.
+bool nsMsgDBView::CustomColumnsInSortAndNotRegistered() {
+  // The initial sort on view open has been started, subsequent user initiated
+  // sort callers can ignore verifying cust col registration.
+  m_checkedCustomColumns = true;
+
+  // DecodeColumnSort must have already created m_sortColumns, otherwise we
+  // can't know, but go on anyway.
+  if (!m_sortColumns.Length()) return false;
+
+  bool custColNotRegistered = false;
+  for (uint32_t i = 0; i < m_sortColumns.Length() && !custColNotRegistered;
+       i++) {
+    if (m_sortColumns[i].mSortType == nsMsgViewSortType::byCustom &&
+        m_sortColumns[i].mColHandler == nullptr)
+      custColNotRegistered = true;
+  }
+
+  return custColNotRegistered;
+}
+// END CUSTOM COLUMNS.
+
+NS_IMETHODIMP
+nsMsgDBView::GetCellText(int32_t aRow, nsTreeColumn* aCol, nsAString& aValue) {
+  const nsAString& colID = aCol->GetId();
+
+  if (!IsValidIndex(aRow)) return NS_MSG_INVALID_DBVIEW_INDEX;
+
+  aValue.Truncate();
+
+  // Attempt to retrieve a custom column handler. If it exists call it and
+  // return.
+  nsIMsgCustomColumnHandler* colHandler = GetColumnHandler(colID);
+
+  if (colHandler) {
+    colHandler->GetCellText(aRow, aCol, aValue);
+    return NS_OK;
+  }
+
+  return CellTextForColumn(aRow, colID, aValue);
+}
+
+NS_IMETHODIMP
+nsMsgDBView::CellTextForColumn(int32_t aRow, const nsAString& aColumnName,
+                               nsAString& aValue) {
+  if (aColumnName.IsEmpty()) {
+    aValue.Truncate();
+    return NS_OK;
+  }
+
+  nsCOMPtr<nsIMsgDBHdr> msgHdr;
+  nsresult rv = GetMsgHdrForViewIndex(aRow, getter_AddRefs(msgHdr));
+
+  if (NS_FAILED(rv) || !msgHdr) {
+    ClearHdrCache();
+    return NS_MSG_INVALID_DBVIEW_INDEX;
+  }
+
+  nsCOMPtr<nsIMsgThread> thread;
+
+  switch (aColumnName.First()) {
+    case 's':
+      if (aColumnName.EqualsLiteral("subjectCol"))
+        rv = FetchSubject(msgHdr, m_flags[aRow], aValue);
+      else if (aColumnName.EqualsLiteral("senderCol"))
+        rv = FetchAuthor(msgHdr, aValue);
+      else if (aColumnName.EqualsLiteral("sizeCol"))
+        rv = FetchSize(msgHdr, aValue);
+      else if (aColumnName.EqualsLiteral("statusCol")) {
+        uint32_t flags;
+        msgHdr->GetFlags(&flags);
+        rv = FetchStatus(flags, aValue);
+      }
+      break;
+    case 'r':
+      if (aColumnName.EqualsLiteral("recipientCol"))
+        rv = FetchRecipients(msgHdr, aValue);
+      else if (aColumnName.EqualsLiteral("receivedCol"))
+        rv = FetchDate(msgHdr, aValue, true);
+      break;
+    case 'd':
+      if (aColumnName.EqualsLiteral("dateCol")) rv = FetchDate(msgHdr, aValue);
+      break;
+    case 'c':
+      if (aColumnName.EqualsLiteral("correspondentCol")) {
+        if (IsOutgoingMsg(msgHdr))
+          rv = FetchRecipients(msgHdr, aValue);
+        else
+          rv = FetchAuthor(msgHdr, aValue);
+      }
+      break;
+    case 'p':
+      if (aColumnName.EqualsLiteral("priorityCol"))
+        rv = FetchPriority(msgHdr, aValue);
+      break;
+    case 'a':
+      if (aColumnName.EqualsLiteral("accountCol"))
+        rv = FetchAccount(msgHdr, aValue);
+      break;
+    case 't':
+      // total msgs in thread column
+      if (aColumnName.EqualsLiteral("totalCol") &&
+          m_viewFlags & nsMsgViewFlagsType::kThreadedDisplay) {
+        if (m_flags[aRow] & MSG_VIEW_FLAG_ISTHREAD) {
+          rv = GetThreadContainingIndex(aRow, getter_AddRefs(thread));
+          if (NS_SUCCEEDED(rv) && thread) {
+            nsAutoString formattedCountString;
+            uint32_t numChildren;
+            thread->GetNumChildren(&numChildren);
+            formattedCountString.AppendInt(numChildren);
+            aValue.Assign(formattedCountString);
+          }
+        }
+      } else if (aColumnName.EqualsLiteral("tagsCol")) {
+        rv = FetchTags(msgHdr, aValue);
+      }
+      break;
+    case 'u':
+      // unread msgs in thread col
+      if (aColumnName.EqualsLiteral("unreadCol") &&
+          m_viewFlags & nsMsgViewFlagsType::kThreadedDisplay) {
+        if (m_flags[aRow] & MSG_VIEW_FLAG_ISTHREAD) {
+          rv = GetThreadContainingIndex(aRow, getter_AddRefs(thread));
+          if (NS_SUCCEEDED(rv) && thread) {
+            nsAutoString formattedCountString;
+            uint32_t numUnreadChildren;
+            thread->GetNumUnreadChildren(&numUnreadChildren);
+            if (numUnreadChildren > 0) {
+              formattedCountString.AppendInt(numUnreadChildren);
+              aValue.Assign(formattedCountString);
+            }
+          }
+        }
+      }
+      break;
+    case 'j': {
+      if (aColumnName.EqualsLiteral("junkStatusCol")) {
+        nsCString junkScoreStr;
+        msgHdr->GetStringProperty("junkscore", junkScoreStr);
+        CopyASCIItoUTF16(junkScoreStr, aValue);
+      }
+      break;
+    }
+    case 'i': {
+      if (aColumnName.EqualsLiteral("idCol")) {
+        nsAutoString keyString;
+        nsMsgKey key;
+        msgHdr->GetMessageKey(&key);
+        keyString.AppendInt((int64_t)key);
+        aValue.Assign(keyString);
+      }
+      break;
+    }
+    case 'l': {
+      if (aColumnName.EqualsLiteral("locationCol")) {
+        nsCOMPtr<nsIMsgFolder> folder;
+        nsresult rv = GetFolderForViewIndex(aRow, getter_AddRefs(folder));
+        NS_ENSURE_SUCCESS(rv, rv);
+        folder->GetPrettyName(aValue);
+      }
+      break;
+    }
+    default:
+      break;
+  }
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsMsgDBView::CellDataForColumns(int32_t aRow,
+                                const nsTArray<nsString>& aColumnNames,
+                                nsAString& aProperties, int32_t* aThreadLevel,
+                                nsTArray<nsString>& _retval) {
+  nsresult rv;
+  _retval.Clear();
+
+  uint32_t count = aColumnNames.Length();
+  _retval.SetCapacity(count);
+  for (nsString column : aColumnNames) {
+    nsString text;
+    rv = CellTextForColumn(aRow, column, text);
+    if (NS_FAILED(rv)) {
+      _retval.Clear();
+      return rv;
+    }
+    _retval.AppendElement(text);
+  }
+
+  rv = GetRowProperties(aRow, aProperties);
+  if (NS_FAILED(rv)) {
+    _retval.Clear();
+    return rv;
+  }
+
+  rv = GetLevel(aRow, aThreadLevel);
+  if (NS_FAILED(rv)) {
+    _retval.Clear();
+    aProperties.Truncate();
+  }
+
+  return rv;
+}
+
+NS_IMETHODIMP
+nsMsgDBView::SetTree(mozilla::dom::XULTreeElement* tree) {
+  mTree = tree;
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsMsgDBView::SetJSTree(nsIMsgJSTree* tree) {
+  mJSTree = tree;
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsMsgDBView::ToggleOpenState(int32_t index) {
+  uint32_t numChanged;
+  nsresult rv = ToggleExpansion(index, &numChanged);
+  NS_ENSURE_SUCCESS(rv, rv);
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsMsgDBView::CycleHeader(nsTreeColumn* aCol) {
+  // Let HandleColumnClick() in threadPane.js handle it
+  // since it will set / clear the sort indicators.
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsMsgDBView::CycleCell(int32_t row, nsTreeColumn* col) {
+  if (!IsValidIndex(row)) {
+    return NS_MSG_INVALID_DBVIEW_INDEX;
+  }
+
+  const nsAString& colID = col->GetId();
+
+  // Attempt to retrieve a custom column handler. If it exists call it and
+  // return.
+  nsIMsgCustomColumnHandler* colHandler = GetColumnHandler(colID);
+
+  if (colHandler) {
+    colHandler->CycleCell(row, col);
+    return NS_OK;
+  }
+
+  // The cyclers below don't work for the grouped header dummy row, currently.
+  // A future implementation should consider both collapsed and expanded state.
+  if (m_viewFlags & nsMsgViewFlagsType::kGroupBySort &&
+      m_flags[row] & MSG_VIEW_FLAG_DUMMY)
+    return NS_OK;
+
+  if (colID.IsEmpty()) return NS_OK;
+
+  switch (colID.First()) {
+    case 'u':
+      if (colID.EqualsLiteral("unreadButtonColHeader")) {
+        ApplyCommandToIndices(nsMsgViewCommandType::toggleMessageRead,
+                              {(nsMsgViewIndex)row});
+      }
+      break;
+    case 't':
+      if (colID.EqualsLiteral("threadCol")) {
+        ExpandAndSelectThreadByIndex(row, false);
+      } else if (colID.EqualsLiteral("tagsCol")) {
+        // XXX Do we want to keep this behaviour but switch it to tags?
+        // We could enumerate over the tags and go to the next one - it looks
+        // to me like this wasn't working before tags landed, so maybe not
+        // worth bothering with.
+      }
+      break;
+    case 'f':
+      if (colID.EqualsLiteral("flaggedCol")) {
+        // toggle the flagged status of the element at row.
+        if (m_flags[row] & nsMsgMessageFlags::Marked) {
+          ApplyCommandToIndices(nsMsgViewCommandType::unflagMessages,
+                                {(nsMsgViewIndex)row});
+        } else {
+          ApplyCommandToIndices(nsMsgViewCommandType::flagMessages,
+                                {(nsMsgViewIndex)row});
+        }
+      }
+      break;
+    case 'j': {
+      if (!colID.EqualsLiteral("junkStatusCol") || !JunkControlsEnabled(row)) {
+        return NS_OK;
+      }
+
+      nsCOMPtr<nsIMsgDBHdr> msgHdr;
+      nsresult rv = GetMsgHdrForViewIndex(row, getter_AddRefs(msgHdr));
+      if (NS_SUCCEEDED(rv) && msgHdr) {
+        nsCString junkScoreStr;
+        rv = msgHdr->GetStringProperty("junkscore", junkScoreStr);
+        if (junkScoreStr.IsEmpty() ||
+            (junkScoreStr.ToInteger(&rv) == nsIJunkMailPlugin::IS_HAM_SCORE)) {
+          ApplyCommandToIndices(nsMsgViewCommandType::junk,
+                                {(nsMsgViewIndex)row});
+        } else {
+          ApplyCommandToIndices(nsMsgViewCommandType::unjunk,
+                                {(nsMsgViewIndex)row});
+        }
+        NS_ASSERTION(NS_SUCCEEDED(rv),
+                     "Converting junkScore to integer failed.");
+      }
+      break;
+    }
+    default:
+      break;
+  }
+
+  return NS_OK;
+}
+
+///////////////////////////////////////////////////////////////////////////
+// end nsITreeView Implementation Methods
+///////////////////////////////////////////////////////////////////////////
+
+NS_IMETHODIMP
+nsMsgDBView::Open(nsIMsgFolder* folder, nsMsgViewSortTypeValue sortType,
+                  nsMsgViewSortOrderValue sortOrder,
+                  nsMsgViewFlagsTypeValue viewFlags, int32_t* pCount) {
+  m_viewFlags = viewFlags;
+  m_sortOrder = sortOrder;
+  m_sortType = sortType;
+
+  nsresult rv;
+  nsCOMPtr<nsIMsgAccountManager> accountManager =
+      do_GetService("@mozilla.org/messenger/account-manager;1", &rv);
+
+  NS_ENSURE_SUCCESS(rv, rv);
+  bool userNeedsToAuthenticate = false;
+  // If we're PasswordProtectLocalCache, then we need to find out if the
+  // server is authenticated.
+  (void)accountManager->GetUserNeedsToAuthenticate(&userNeedsToAuthenticate);
+  if (userNeedsToAuthenticate) return NS_MSG_USER_NOT_AUTHENTICATED;
+
+  if (folder) {
+    // Search view will have a null folder.
+    nsCOMPtr<nsIDBFolderInfo> folderInfo;
+    rv = folder->GetDBFolderInfoAndDB(getter_AddRefs(folderInfo),
+                                      getter_AddRefs(m_db));
+    NS_ENSURE_SUCCESS(rv, rv);
+    nsCOMPtr<nsIMsgDBService> msgDBService =
+        do_GetService("@mozilla.org/msgDatabase/msgDBService;1", &rv);
+    NS_ENSURE_SUCCESS(rv, rv);
+    msgDBService->RegisterPendingListener(folder, this);
+    m_folder = folder;
+
+    if (!m_viewFolder) {
+      // There is never a viewFolder already set except for the single folder
+      // saved search case, where the backing folder m_folder is different from
+      // the m_viewFolder with its own dbFolderInfo state.
+      m_viewFolder = folder;
+    }
+
+    SetMRUTimeForFolder(m_viewFolder);
+
+    RestoreSortInfo();
+
+    // Determine if we are in a news folder or not. If yes, we'll show lines
+    // instead of size, and special icons in the thread pane.
+    nsCOMPtr<nsIMsgIncomingServer> server;
+    rv = folder->GetServer(getter_AddRefs(server));
+    NS_ENSURE_SUCCESS(rv, rv);
+    nsCString type;
+    rv = server->GetType(type);
+    NS_ENSURE_SUCCESS(rv, rv);
+
+    // I'm not sure this is correct, because XF virtual folders with mixed news
+    // and mail can have this set.
+    mIsNews = type.LowerCaseEqualsLiteral("nntp");
+
+    // Default to a virtual folder if folder not set, since synthetic search
+    // views may not have a folder.
+    uint32_t folderFlags = nsMsgFolderFlags::Virtual;
+    if (folder) folder->GetFlags(&folderFlags);
+
+    mIsXFVirtual = folderFlags & nsMsgFolderFlags::Virtual;
+    if (!mIsXFVirtual && type.LowerCaseEqualsLiteral("rss")) mIsRss = true;
+
+    // Special case nntp --> news since we'll break themes if we try to be
+    // consistent.
+    if (mIsNews)
+      mMessageType.AssignLiteral("news");
+    else
+      CopyUTF8toUTF16(type, mMessageType);
+
+    GetImapDeleteModel(nullptr);
+
+    nsCOMPtr<nsIPrefBranch> prefs(do_GetService(NS_PREFSERVICE_CONTRACTID));
+    if (prefs) {
+      prefs->GetBoolPref("mailnews.sort_threads_by_root", &mSortThreadsByRoot);
+      if (mIsNews)
+        prefs->GetBoolPref("news.show_size_in_lines", &mShowSizeInLines);
+    }
+  }
+
+  nsTArray<RefPtr<nsIMsgIdentity>> identities;
+  rv = accountManager->GetAllIdentities(identities);
+  NS_ENSURE_SUCCESS(rv, rv);
+
+  for (auto identity : identities) {
+    if (!identity) continue;
+
+    nsCString email;
+    identity->GetEmail(email);
+    if (!email.IsEmpty()) {
+      ToLowerCaseDropPlusAddessing(email);
+      mEmails.PutEntry(email);
+    }
+
+    identity->GetReplyTo(email);
+    if (!email.IsEmpty()) {
+      ToLowerCaseDropPlusAddessing(email);
+      mEmails.PutEntry(email);
+    }
+  }
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsMsgDBView::Close() {
+  int32_t oldSize = GetSize();
+  // This is important, because the tree will ask us for our row count, which
+  // gets determined from the number of keys.
+  m_keys.Clear();
+  // Be consistent.
+  m_flags.Clear();
+  m_levels.Clear();
+
+  // Clear these out since they no longer apply if we're switching a folder
+  mJunkHdrs.Clear();
+
+  // This needs to happen after we remove all the keys, since RowCountChanged()
+  // will call our GetRowCount().
+  if (mTree) mTree->RowCountChanged(0, -oldSize);
+  if (mJSTree) mJSTree->RowCountChanged(0, -oldSize);
+
+  ClearHdrCache();
+  if (m_db) {
+    m_db->RemoveListener(this);
+    m_db = nullptr;
+  }
+  if (m_folder) {
+    nsresult rv;
+    nsCOMPtr<nsIMsgDBService> msgDBService =
+        do_GetService("@mozilla.org/msgDatabase/msgDBService;1", &rv);
+    NS_ENSURE_SUCCESS(rv, rv);
+    msgDBService->UnregisterPendingListener(this);
+  }
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsMsgDBView::OpenWithHdrs(nsIMsgEnumerator* aHeaders,
+                          nsMsgViewSortTypeValue aSortType,
+                          nsMsgViewSortOrderValue aSortOrder,
+                          nsMsgViewFlagsTypeValue aViewFlags, int32_t* aCount) {
+  NS_ASSERTION(false, "not implemented");
+  return NS_ERROR_NOT_IMPLEMENTED;
+}
+
+NS_IMETHODIMP
+nsMsgDBView::Init(nsIMessenger* aMessengerInstance, nsIMsgWindow* aMsgWindow,
+                  nsIMsgDBViewCommandUpdater* aCmdUpdater) {
+  mMessengerWeak = do_GetWeakReference(aMessengerInstance);
+  mMsgWindowWeak = do_GetWeakReference(aMsgWindow);
+  mCommandUpdater = do_GetWeakReference(aCmdUpdater);
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsMsgDBView::SetSuppressCommandUpdating(bool aSuppressCommandUpdating) {
+  mSuppressCommandUpdating = aSuppressCommandUpdating;
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsMsgDBView::GetSuppressCommandUpdating(bool* aSuppressCommandUpdating) {
+  *aSuppressCommandUpdating = mSuppressCommandUpdating;
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsMsgDBView::SetSuppressMsgDisplay(bool aSuppressDisplay) {
+  mSuppressMsgDisplay = aSuppressDisplay;
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsMsgDBView::GetSuppressMsgDisplay(bool* aSuppressDisplay) {
+  *aSuppressDisplay = mSuppressMsgDisplay;
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsMsgDBView::GetUsingLines(bool* aUsingLines) {
+  *aUsingLines = mShowSizeInLines;
+  return NS_OK;
+}
+
+int CompareViewIndices(const void* v1, const void* v2, void*) {
+  nsMsgViewIndex i1 = *(nsMsgViewIndex*)v1;
+  nsMsgViewIndex i2 = *(nsMsgViewIndex*)v2;
+  return i1 - i2;
+}
+
+// Array<nsMsgViewIndex> getIndicesForSelection();
+NS_IMETHODIMP
+nsMsgDBView::GetIndicesForSelection(nsTArray<nsMsgViewIndex>& indices) {
+  indices.Clear();
+  if (mTreeSelection) {
+    int32_t viewSize = GetSize();
+    int32_t count;
+    mTreeSelection->GetCount(&count);
+    indices.SetCapacity(count);
+    int32_t selectionCount;
+    mTreeSelection->GetRangeCount(&selectionCount);
+    for (int32_t i = 0; i < selectionCount; i++) {
+      int32_t startRange = -1;
+      int32_t endRange = -1;
+      mTreeSelection->GetRangeAt(i, &startRange, &endRange);
+      if (startRange >= 0 && startRange < viewSize) {
+        for (int32_t rangeIndex = startRange;
+             rangeIndex <= endRange && rangeIndex < viewSize; rangeIndex++) {
+          indices.AppendElement(rangeIndex);
+        }
+      }
+    }
+
+    NS_ASSERTION(indices.Length() == uint32_t(count),
+                 "selection count is wrong");
+  } else {
+    // If there is no tree selection object then we must be in stand alone
+    // message mode. In that case the selected indices are really just the
+    // current message key.
+    nsMsgViewIndex viewIndex = FindViewIndex(m_currentlyDisplayedMsgKey);
+    if (viewIndex != nsMsgViewIndex_None) indices.AppendElement(viewIndex);
+  }
+
+  return NS_OK;
+}
+
+// Array<nsIMsgDBHdr> getSelectedMsgHdrs();
+NS_IMETHODIMP
+nsMsgDBView::GetSelectedMsgHdrs(nsTArray<RefPtr<nsIMsgDBHdr>>& aResult) {
+  nsMsgViewIndexArray selection;
+  aResult.Clear();
+  nsresult rv = GetIndicesForSelection(selection);
+  NS_ENSURE_SUCCESS(rv, rv);
+  return GetHeadersFromSelection(selection, aResult);
+}
+
+NS_IMETHODIMP
+nsMsgDBView::GetURIsForSelection(nsTArray<nsCString>& uris) {
+  uris.Clear();
+  AutoTArray<RefPtr<nsIMsgDBHdr>, 1> messages;
+  nsresult rv = GetSelectedMsgHdrs(messages);
+  NS_ENSURE_SUCCESS(rv, rv);
+  uris.SetCapacity(messages.Length());
+  for (nsIMsgDBHdr* msgHdr : messages) {
+    nsCString tmpUri;
+    nsCOMPtr<nsIMsgFolder> folder;
+    nsMsgKey msgKey;
+    msgHdr->GetMessageKey(&msgKey);
+    msgHdr->GetFolder(getter_AddRefs(folder));
+    rv = GenerateURIForMsgKey(msgKey, folder, tmpUri);
+    NS_ENSURE_SUCCESS(rv, rv);
+    uris.AppendElement(tmpUri);
+  }
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsMsgDBView::GetURIForViewIndex(nsMsgViewIndex index, nsACString& result) {
+  nsresult rv;
+  nsCOMPtr<nsIMsgFolder> folder = m_folder;
+  if (!folder) {
+    rv = GetFolderForViewIndex(index, getter_AddRefs(folder));
+    NS_ENSURE_SUCCESS(rv, rv);
+  }
+
+  if (index == nsMsgViewIndex_None || index >= m_flags.Length() ||
+      m_flags[index] & MSG_VIEW_FLAG_DUMMY) {
+    return NS_MSG_INVALID_DBVIEW_INDEX;
+  }
+
+  return GenerateURIForMsgKey(m_keys[index], folder, result);
+}
+
+NS_IMETHODIMP
+nsMsgDBView::DoCommandWithFolder(nsMsgViewCommandTypeValue command,
+                                 nsIMsgFolder* destFolder) {
+  NS_ENSURE_ARG_POINTER(destFolder);
+
+  nsMsgViewIndexArray selection;
+  GetIndicesForSelection(selection);
+
+  nsresult rv = NS_OK;
+  switch (command) {
+    case nsMsgViewCommandType::copyMessages:
+    case nsMsgViewCommandType::moveMessages:
+      rv = ApplyCommandToIndicesWithFolder(command, selection, destFolder);
+      NoteChange(0, 0, nsMsgViewNotificationCode::none);
+      break;
+    default:
+      NS_ASSERTION(false, "invalid command type");
+      rv = NS_ERROR_UNEXPECTED;
+      break;
+  }
+
+  return rv;
+}
+
+NS_IMETHODIMP
+nsMsgDBView::DoCommand(nsMsgViewCommandTypeValue command) {
+  nsMsgViewIndexArray selection;
+  GetIndicesForSelection(selection);
+
+  nsCOMPtr<nsIMsgWindow> msgWindow(do_QueryReferent(mMsgWindowWeak));
+
+  nsresult rv = NS_OK;
+  switch (command) {
+    case nsMsgViewCommandType::downloadSelectedForOffline:
+      return DownloadForOffline(msgWindow, selection);
+    case nsMsgViewCommandType::downloadFlaggedForOffline:
+      return DownloadFlaggedForOffline(msgWindow);
+    case nsMsgViewCommandType::markMessagesRead:
+    case nsMsgViewCommandType::markMessagesUnread:
+    case nsMsgViewCommandType::toggleMessageRead:
+    case nsMsgViewCommandType::flagMessages:
+    case nsMsgViewCommandType::unflagMessages:
+    case nsMsgViewCommandType::deleteMsg:
+    case nsMsgViewCommandType::undeleteMsg:
+    case nsMsgViewCommandType::deleteNoTrash:
+    case nsMsgViewCommandType::markThreadRead:
+    case nsMsgViewCommandType::junk:
+    case nsMsgViewCommandType::unjunk:
+      rv = ApplyCommandToIndices(command, selection);
+      NoteChange(0, 0, nsMsgViewNotificationCode::none);
+      break;
+    case nsMsgViewCommandType::selectAll:
+      if (mTreeSelection) {
+        // If in threaded mode, we need to expand all before selecting.
+        if (m_viewFlags & nsMsgViewFlagsType::kThreadedDisplay)
+          rv = ExpandAll();
+
+        mTreeSelection->SelectAll();
+        if (mTree) mTree->Invalidate();
+        if (mJSTree) mJSTree->Invalidate();
+      }
+      break;
+    case nsMsgViewCommandType::selectThread:
+      rv = ExpandAndSelectThread();
+      break;
+    case nsMsgViewCommandType::selectFlagged:
+      if (!mTreeSelection) {
+        rv = NS_ERROR_UNEXPECTED;
+      } else {
+        mTreeSelection->SetSelectEventsSuppressed(true);
+        mTreeSelection->ClearSelection();
+        // XXX ExpandAll?
+        uint32_t numIndices = GetSize();
+        for (uint32_t curIndex = 0; curIndex < numIndices; curIndex++) {
+          if (m_flags[curIndex] & nsMsgMessageFlags::Marked)
+            mTreeSelection->ToggleSelect(curIndex);
+        }
+
+        mTreeSelection->SetSelectEventsSuppressed(false);
+      }
+      break;
+    case nsMsgViewCommandType::markAllRead:
+      if (m_folder) {
+        SetSuppressChangeNotifications(true);
+        rv = m_folder->MarkAllMessagesRead(msgWindow);
+        SetSuppressChangeNotifications(false);
+        if (mTree) mTree->Invalidate();
+        if (mJSTree) mJSTree->Invalidate();
+      }
+      break;
+    case nsMsgViewCommandType::toggleThreadWatched:
+      rv = ToggleWatched(selection);
+      break;
+    case nsMsgViewCommandType::expandAll:
+      rv = ExpandAll();
+      m_viewFlags |= nsMsgViewFlagsType::kExpandAll;
+      SetViewFlags(m_viewFlags);
+      if (mTree) mTree->Invalidate();
+      if (mJSTree) mJSTree->Invalidate();
+
+      break;
+    case nsMsgViewCommandType::collapseAll:
+      rv = CollapseAll();
+      m_viewFlags &= ~nsMsgViewFlagsType::kExpandAll;
+      SetViewFlags(m_viewFlags);
+      if (mTree) mTree->Invalidate();
+      if (mJSTree) mJSTree->Invalidate();
+
+      break;
+    default:
+      NS_ASSERTION(false, "invalid command type");
+      rv = NS_ERROR_UNEXPECTED;
+      break;
+  }
+
+  return rv;
+}
+
+bool nsMsgDBView::ServerSupportsFilterAfterTheFact() {
+  // Cross folder virtual folders might not have a folder set.
+  if (!m_folder) return false;
+
+  nsCOMPtr<nsIMsgIncomingServer> server;
+  nsresult rv = m_folder->GetServer(getter_AddRefs(server));
+  // Unexpected.
+  if (NS_FAILED(rv)) return false;
+
+  // Filter after the fact is implement using search so if you can't search,
+  // you can't filter after the fact.
+  bool canSearch;
+  rv = server->GetCanSearchMessages(&canSearch);
+  // Unexpected.
+  if (NS_FAILED(rv)) return false;
+
+  return canSearch;
+}
+
+NS_IMETHODIMP
+nsMsgDBView::GetCommandStatus(nsMsgViewCommandTypeValue command,
+                              bool* selectable_p,
+                              nsMsgViewCommandCheckStateValue* selected_p) {
+  nsresult rv = NS_OK;
+
+  bool haveSelection;
+  int32_t rangeCount;
+  nsMsgViewIndexArray selection;
+  GetIndicesForSelection(selection);
+  // If range count is non-zero, we have at least one item selected, so we
+  // have a selection.
+  if (mTreeSelection &&
+      NS_SUCCEEDED(mTreeSelection->GetRangeCount(&rangeCount)) &&
+      rangeCount > 0) {
+    haveSelection = NonDummyMsgSelected(selection);
+  } else {
+    // If we don't have a tree selection we must be in stand alone mode.
+    haveSelection = IsValidIndex(m_currentlyDisplayedViewIndex);
+  }
+
+  switch (command) {
+    case nsMsgViewCommandType::deleteMsg:
+    case nsMsgViewCommandType::deleteNoTrash: {
+      bool canDelete;
+      if (m_folder &&
+          NS_SUCCEEDED(m_folder->GetCanDeleteMessages(&canDelete)) &&
+          !canDelete) {
+        *selectable_p = false;
+      } else {
+        *selectable_p = haveSelection;
+      }
+      break;
+    }
+    case nsMsgViewCommandType::applyFilters:
+      // Disable if no messages.
+      // XXX todo, check that we have filters, and at least one is enabled.
+      *selectable_p = GetSize();
+      if (*selectable_p) *selectable_p = ServerSupportsFilterAfterTheFact();
+
+      break;
+    case nsMsgViewCommandType::runJunkControls:
+      // Disable if no messages.
+      // XXX todo, check that we have JMC enabled?
+      *selectable_p = GetSize() && JunkControlsEnabled(nsMsgViewIndex_None);
+      break;
+    case nsMsgViewCommandType::deleteJunk: {
+      // Disable if no messages, or if we can't delete (like news and
+      // certain imap folders).
+      bool canDelete;
+      *selectable_p =
+          GetSize() && m_folder &&
+          NS_SUCCEEDED(m_folder->GetCanDeleteMessages(&canDelete)) && canDelete;
+      break;
+    }
+    case nsMsgViewCommandType::markMessagesRead:
+    case nsMsgViewCommandType::markMessagesUnread:
+    case nsMsgViewCommandType::toggleMessageRead:
+    case nsMsgViewCommandType::flagMessages:
+    case nsMsgViewCommandType::unflagMessages:
+    case nsMsgViewCommandType::toggleThreadWatched:
+    case nsMsgViewCommandType::markThreadRead:
+    case nsMsgViewCommandType::downloadSelectedForOffline:
+      *selectable_p = haveSelection;
+      break;
+    case nsMsgViewCommandType::junk:
+    case nsMsgViewCommandType::unjunk:
+      *selectable_p = haveSelection && !selection.IsEmpty() &&
+                      JunkControlsEnabled(selection[0]);
+      break;
+    case nsMsgViewCommandType::cmdRequiringMsgBody:
+      *selectable_p =
+          haveSelection && (!WeAreOffline() || OfflineMsgSelected(selection));
+      break;
+    case nsMsgViewCommandType::downloadFlaggedForOffline:
+    case nsMsgViewCommandType::markAllRead:
+      *selectable_p = true;
+      break;
+    default:
+      NS_ASSERTION(false, "invalid command type");
+      rv = NS_ERROR_FAILURE;
+  }
+
+  return rv;
+}
+
+// This method needs to be overridden by the various view classes
+// that have different kinds of threads. For example, in a
+// threaded quick search db view, we'd only want to include children
+// of the thread that fit the view (IMO). And when we have threaded
+// cross folder views, we would include all the children of the
+// cross-folder thread.
+nsresult nsMsgDBView::ListCollapsedChildren(
+    nsMsgViewIndex viewIndex, nsTArray<RefPtr<nsIMsgDBHdr>>& messageArray) {
+  nsCOMPtr<nsIMsgDBHdr> msgHdr;
+  nsCOMPtr<nsIMsgThread> thread;
+  GetMsgHdrForViewIndex(viewIndex, getter_AddRefs(msgHdr));
+  if (!msgHdr) {
+    NS_ASSERTION(false, "couldn't find message to expand");
+    return NS_MSG_MESSAGE_NOT_FOUND;
+  }
+
+  nsresult rv = GetThreadContainingMsgHdr(msgHdr, getter_AddRefs(thread));
+  NS_ENSURE_SUCCESS(rv, rv);
+  uint32_t numChildren;
+  thread->GetNumChildren(&numChildren);
+  for (uint32_t i = 1; i < numChildren && NS_SUCCEEDED(rv); i++) {
+    nsCOMPtr<nsIMsgDBHdr> msgHdr;
+    rv = thread->GetChildHdrAt(i, getter_AddRefs(msgHdr));
+    if (msgHdr) {
+      messageArray.AppendElement(msgHdr);
+    }
+  }
+
+  return rv;
+}
+
+bool nsMsgDBView::OperateOnMsgsInCollapsedThreads() {
+  if (!mJSTree && mTreeSelection) {
+    RefPtr<mozilla::dom::XULTreeElement> selTree;
+    mTreeSelection->GetTree(getter_AddRefs(selTree));
+    // No tree means stand-alone message window.
+    if (!selTree) return false;
+  }
+
+  nsresult rv = NS_OK;
+  nsCOMPtr<nsIPrefBranch> prefBranch(
+      do_GetService(NS_PREFSERVICE_CONTRACTID, &rv));
+  NS_ENSURE_SUCCESS(rv, false);
+
+  bool includeCollapsedMsgs = false;
+  prefBranch->GetBoolPref("mail.operate_on_msgs_in_collapsed_threads",
+                          &includeCollapsedMsgs);
+  return includeCollapsedMsgs;
+}
+
+nsresult nsMsgDBView::GetHeadersFromSelection(
+    nsTArray<nsMsgViewIndex> const& selection,
+    nsTArray<RefPtr<nsIMsgDBHdr>>& hdrs) {
+  hdrs.Clear();
+  hdrs.SetCapacity(selection.Length());  // Best guess.
+  nsresult rv = NS_OK;
+
+  // Don't include collapsed messages if the front end failed to summarize
+  // the selection.
+  bool includeCollapsedMsgs =
+      OperateOnMsgsInCollapsedThreads() && !mSummarizeFailed;
+
+  for (nsMsgViewIndex viewIndex : selection) {
+    if (NS_FAILED(rv)) {
+      break;
+    }
+    if (viewIndex == nsMsgViewIndex_None) {
+      continue;
+    }
+
+    uint32_t viewIndexFlags = m_flags[viewIndex];
+    if (viewIndexFlags & MSG_VIEW_FLAG_DUMMY) {
+      // If collapsed dummy header selected, list its children.
+      if (includeCollapsedMsgs && viewIndexFlags & nsMsgMessageFlags::Elided &&
+          m_viewFlags & nsMsgViewFlagsType::kThreadedDisplay)
+        rv = ListCollapsedChildren(viewIndex, hdrs);
+
+      continue;
+    }
+
+    nsCOMPtr<nsIMsgDBHdr> msgHdr;
+    rv = GetMsgHdrForViewIndex(viewIndex, getter_AddRefs(msgHdr));
+    if (NS_SUCCEEDED(rv) && msgHdr) {
+      hdrs.AppendElement(msgHdr);
+      if (includeCollapsedMsgs && viewIndexFlags & nsMsgMessageFlags::Elided &&
+          viewIndexFlags & MSG_VIEW_FLAG_HASCHILDREN &&
+          m_viewFlags & nsMsgViewFlagsType::kThreadedDisplay) {
+        rv = ListCollapsedChildren(viewIndex, hdrs);
+      }
+    }
+  }
+
+  return rv;
+}
+
+nsresult nsMsgDBView::CopyMessages(nsIMsgWindow* window,
+                                   nsTArray<nsMsgViewIndex> const& selection,
+                                   bool isMove, nsIMsgFolder* destFolder) {
+  if (m_deletingRows) {
+    NS_ASSERTION(false, "Last move did not complete");
+    return NS_OK;
+  }
+
+  nsresult rv;
+  NS_ENSURE_ARG_POINTER(destFolder);
+
+  AutoTArray<RefPtr<nsIMsgDBHdr>, 1> hdrs;
+  rv = GetHeadersFromSelection(selection, hdrs);
+  NS_ENSURE_SUCCESS(rv, rv);
+
+  m_deletingRows = isMove && mDeleteModel != nsMsgImapDeleteModels::IMAPDelete;
+  if (m_deletingRows) {
+    mIndicesToNoteChange.AppendElements(selection);
+  }
+
+  nsCOMPtr<nsIMsgCopyService> copyService =
+      do_GetService("@mozilla.org/messenger/messagecopyservice;1", &rv);
+  NS_ENSURE_SUCCESS(rv, rv);
+
+  return copyService->CopyMessages(m_folder /* source folder */, hdrs,
+                                   destFolder, isMove, nullptr /* listener */,
+                                   window, true /* allow Undo */);
+}
+
+nsresult nsMsgDBView::ApplyCommandToIndicesWithFolder(
+    nsMsgViewCommandTypeValue command,
+    nsTArray<nsMsgViewIndex> const& selection, nsIMsgFolder* destFolder) {
+  nsresult rv = NS_OK;
+  NS_ENSURE_ARG_POINTER(destFolder);
+
+  nsCOMPtr<nsIMsgWindow> msgWindow(do_QueryReferent(mMsgWindowWeak));
+  switch (command) {
+    case nsMsgViewCommandType::copyMessages:
+      NS_ASSERTION(!(m_folder == destFolder),
+                   "The source folder and the destination folder are the same");
+      if (m_folder != destFolder)
+        rv = CopyMessages(msgWindow, selection, false /* isMove */, destFolder);
+
+      break;
+    case nsMsgViewCommandType::moveMessages:
+      NS_ASSERTION(!(m_folder == destFolder),
+                   "The source folder and the destination folder are the same");
+      if (m_folder != destFolder)
+        rv = CopyMessages(msgWindow, selection, true /* isMove */, destFolder);
+
+      break;
+    default:
+      NS_ASSERTION(false, "unhandled command");
+      rv = NS_ERROR_UNEXPECTED;
+      break;
+  }
+
+  return rv;
+}
+
+NS_IMETHODIMP
+nsMsgDBView::ApplyCommandToIndices(nsMsgViewCommandTypeValue command,
+                                   nsTArray<nsMsgViewIndex> const& selection) {
+  if (selection.IsEmpty()) {
+    // Return quietly, just in case/
+    return NS_OK;
+  }
+
+  nsCOMPtr<nsIMsgFolder> folder;
+  nsresult rv = GetFolderForViewIndex(selection[0], getter_AddRefs(folder));
+  nsCOMPtr<nsIMsgWindow> msgWindow(do_QueryReferent(mMsgWindowWeak));
+  if (command == nsMsgViewCommandType::deleteMsg)
+    return DeleteMessages(msgWindow, selection, false);
+
+  if (command == nsMsgViewCommandType::deleteNoTrash)
+    return DeleteMessages(msgWindow, selection, true);
+
+  nsTArray<nsMsgKey> imapUids;
+  nsCOMPtr<nsIMsgImapMailFolder> imapFolder = do_QueryInterface(folder);
+  bool thisIsImapFolder = (imapFolder != nullptr);
+  nsCOMPtr<nsIJunkMailPlugin> junkPlugin;
+
+  // If this is a junk command, get the junk plugin.
+  if (command == nsMsgViewCommandType::junk ||
+      command == nsMsgViewCommandType::unjunk) {
+    // Get the folder from the first item; we assume that
+    // all messages in the view are from the same folder (no
+    // more junk status column in the 'search messages' dialog
+    // like in earlier versions...).
+    nsCOMPtr<nsIMsgIncomingServer> server;
+    rv = folder->GetServer(getter_AddRefs(server));
+    NS_ENSURE_SUCCESS(rv, rv);
+
+    nsCOMPtr<nsIMsgFilterPlugin> filterPlugin;
+    rv = server->GetSpamFilterPlugin(getter_AddRefs(filterPlugin));
+    NS_ENSURE_SUCCESS(rv, rv);
+
+    junkPlugin = do_QueryInterface(filterPlugin, &rv);
+    NS_ENSURE_SUCCESS(rv, rv);
+  }
+
+  folder->EnableNotifications(nsIMsgFolder::allMessageCountNotifications,
+                              false);
+
+  // No sense going through the code that handles messages in collasped threads
+  // for mark thread read.
+  if (command == nsMsgViewCommandType::markThreadRead) {
+    for (nsMsgViewIndex viewIndex : selection) {
+      SetThreadOfMsgReadByIndex(viewIndex, imapUids, true);
+    }
+  } else {
+    // Turn the selection into an array of msg hdrs. This may include messages
+    // in collapsed threads
+    AutoTArray<RefPtr<nsIMsgDBHdr>, 1> messages;
+    rv = GetHeadersFromSelection(selection, messages);
+    NS_ENSURE_SUCCESS(rv, rv);
+    uint32_t length = messages.Length();
+
+    if (thisIsImapFolder) {
+      imapUids.SetLength(length);
+    }
+
+    for (uint32_t i = 0; i < length; i++) {
+      nsMsgKey msgKey;
+      nsCOMPtr<nsIMsgDBHdr> msgHdr(messages[i]);
+      msgHdr->GetMessageKey(&msgKey);
+      if (thisIsImapFolder) imapUids[i] = msgKey;
+
+      switch (command) {
+        case nsMsgViewCommandType::junk:
+          mNumMessagesRemainingInBatch++;
+          mJunkHdrs.AppendElement(msgHdr);
+          rv = SetMsgHdrJunkStatus(junkPlugin.get(), msgHdr,
+                                   nsIJunkMailPlugin::JUNK);
+          break;
+        case nsMsgViewCommandType::unjunk:
+          mNumMessagesRemainingInBatch++;
+          mJunkHdrs.AppendElement(msgHdr);
+          rv = SetMsgHdrJunkStatus(junkPlugin.get(), msgHdr,
+                                   nsIJunkMailPlugin::GOOD);
+          break;
+        case nsMsgViewCommandType::toggleMessageRead:
+        case nsMsgViewCommandType::undeleteMsg:
+        case nsMsgViewCommandType::markMessagesRead:
+        case nsMsgViewCommandType::markMessagesUnread:
+        case nsMsgViewCommandType::unflagMessages:
+        case nsMsgViewCommandType::flagMessages:
+          // This is completely handled in the code below.
+          break;
+        default:
+          NS_ERROR("unhandled command");
+          break;
+      }
+    }
+
+    switch (command) {
+      case nsMsgViewCommandType::toggleMessageRead: {
+        if (messages.IsEmpty()) break;
+
+        uint32_t msgFlags;
+        messages[0]->GetFlags(&msgFlags);
+        folder->MarkMessagesRead(messages,
+                                 !(msgFlags & nsMsgMessageFlags::Read));
+        break;
+      }
+      case nsMsgViewCommandType::markMessagesRead:
+      case nsMsgViewCommandType::markMessagesUnread:
+        folder->MarkMessagesRead(
+            messages, command == nsMsgViewCommandType::markMessagesRead);
+        break;
+      case nsMsgViewCommandType::unflagMessages:
+      case nsMsgViewCommandType::flagMessages:
+        folder->MarkMessagesFlagged(
+            messages, command == nsMsgViewCommandType::flagMessages);
+        break;
+      default:
+        break;
+    }
+
+    // Provide junk-related batch notifications.
+    if (command == nsMsgViewCommandType::junk ||
+        command == nsMsgViewCommandType::unjunk) {
+      nsCOMPtr<nsIMsgFolderNotificationService> notifier(
+          do_GetService("@mozilla.org/messenger/msgnotificationservice;1"));
+      if (notifier) {
+        notifier->NotifyMsgsJunkStatusChanged(messages);
+      }
+    }
+  }
+
+  folder->EnableNotifications(nsIMsgFolder::allMessageCountNotifications, true);
+
+  if (thisIsImapFolder) {
+    imapMessageFlagsType flags = kNoImapMsgFlag;
+    bool addFlags = false;
+    nsCOMPtr<nsIMsgWindow> msgWindow(do_QueryReferent(mMsgWindowWeak));
+    switch (command) {
+      case nsMsgViewCommandType::markThreadRead:
+        flags |= kImapMsgSeenFlag;
+        addFlags = true;
+        break;
+      case nsMsgViewCommandType::undeleteMsg:
+        flags = kImapMsgDeletedFlag;
+        addFlags = false;
+        break;
+      case nsMsgViewCommandType::junk:
+        return imapFolder->StoreCustomKeywords(msgWindow, "Junk"_ns,
+                                               "NonJunk"_ns, imapUids, nullptr);
+      case nsMsgViewCommandType::unjunk: {
+        nsCOMPtr<nsIMsgDBHdr> msgHdr;
+        GetHdrForFirstSelectedMessage(getter_AddRefs(msgHdr));
+        uint32_t msgFlags = 0;
+        if (msgHdr) msgHdr->GetFlags(&msgFlags);
+
+        if (msgFlags & nsMsgMessageFlags::IMAPDeleted)
+          imapFolder->StoreImapFlags(kImapMsgDeletedFlag, false, imapUids,
+                                     nullptr);
+
+        return imapFolder->StoreCustomKeywords(msgWindow, "NonJunk"_ns,
+                                               "Junk"_ns, imapUids, nullptr);
+      }
+      default:
+        break;
+    }
+
+    // Can't get here without thisIsImapThreadPane == TRUE.
+    if (flags != kNoImapMsgFlag) {
+      imapFolder->StoreImapFlags(flags, addFlags, imapUids, nullptr);
+    }
+  }
+
+  return rv;
+}
+
+/**
+ * View modifications methods by index.
+ */
+
+// This method just removes the specified line from the view. It does
+// NOT delete it from the database.
+nsresult nsMsgDBView::RemoveByIndex(nsMsgViewIndex index) {
+  if (!IsValidIndex(index)) return NS_MSG_INVALID_DBVIEW_INDEX;
+
+  m_keys.RemoveElementAt(index);
+  m_flags.RemoveElementAt(index);
+  m_levels.RemoveElementAt(index);
+
+  // The call to NoteChange() has to happen after we remove the key as
+  // NoteChange() will call RowCountChanged() which will call our GetRowCount().
+  // An example where view is not the listener - D&D messages.
+  if (!m_deletingRows)
+    NoteChange(index, -1, nsMsgViewNotificationCode::insertOrDelete);
+
+  return NS_OK;
+}
+
+nsresult nsMsgDBView::DeleteMessages(nsIMsgWindow* window,
+                                     nsTArray<nsMsgViewIndex> const& selection,
+                                     bool deleteStorage) {
+  if (m_deletingRows) {
+    NS_WARNING("Last delete did not complete");
+    return NS_OK;
+  }
+
+  nsresult rv;
+  AutoTArray<RefPtr<nsIMsgDBHdr>, 1> hdrs;
+  rv = GetHeadersFromSelection(selection, hdrs);
+  NS_ENSURE_SUCCESS(rv, rv);
+
+  const char* warnCollapsedPref = "mail.warn_on_collapsed_thread_operation";
+  const char* warnShiftDelPref = "mail.warn_on_shift_delete";
+  const char* warnNewsPref = "news.warn_on_delete";
+  const char* warnTrashDelPref = "mail.warn_on_delete_from_trash";
+  const char* activePref = nullptr;
+  nsString warningName;
+  nsCOMPtr<nsIPrefBranch> prefBranch(
+      do_GetService(NS_PREFSERVICE_CONTRACTID, &rv));
+  NS_ENSURE_SUCCESS(rv, rv);
+
+  bool trashFolder = false;
+  rv = m_folder->GetFlag(nsMsgFolderFlags::Trash, &trashFolder);
+  NS_ENSURE_SUCCESS(rv, rv);
+
+  if (trashFolder) {
+    bool pref = false;
+    prefBranch->GetBoolPref(warnTrashDelPref, &pref);
+    if (pref) {
+      activePref = warnTrashDelPref;
+      warningName.AssignLiteral("confirmMsgDelete.deleteFromTrash.desc");
+    }
+  }
+
+  if (!activePref && (selection.Length() != hdrs.Length())) {
+    bool pref = false;
+    prefBranch->GetBoolPref(warnCollapsedPref, &pref);
+    if (pref) {
+      activePref = warnCollapsedPref;
+      warningName.AssignLiteral("confirmMsgDelete.collapsed.desc");
+    }
+  }
+
+  if (!activePref && deleteStorage && !trashFolder) {
+    bool pref = false;
+    prefBranch->GetBoolPref(warnShiftDelPref, &pref);
+    if (pref) {
+      activePref = warnShiftDelPref;
+      warningName.AssignLiteral("confirmMsgDelete.deleteNoTrash.desc");
+    }
+  }
+
+  if (!activePref && mIsNews) {
+    bool pref = false;
+    prefBranch->GetBoolPref(warnNewsPref, &pref);
+    if (pref) {
+      activePref = warnNewsPref;
+      warningName.AssignLiteral("confirmMsgDelete.deleteNoTrash.desc");
+    }
+  }
+
+  if (activePref) {
+    nsCOMPtr<nsIPrompt> dialog;
+
+    nsCOMPtr<nsIWindowWatcher> wwatch(
+        do_GetService(NS_WINDOWWATCHER_CONTRACTID, &rv));
+    NS_ENSURE_SUCCESS(rv, rv);
+
+    rv = wwatch->GetNewPrompter(0, getter_AddRefs(dialog));
+    NS_ENSURE_SUCCESS(rv, rv);
+    // "Don't ask..." - unchecked by default.
+    bool dontAsk = false;
+    int32_t buttonPressed = 0;
+
+    nsString dialogTitle;
+    nsString confirmString;
+    nsString checkboxText;
+    nsString buttonApplyNowText;
+    GetString(u"confirmMsgDelete.title", dialogTitle);
+    GetString(u"confirmMsgDelete.dontAsk.label", checkboxText);
+    GetString(u"confirmMsgDelete.delete.label", buttonApplyNowText);
+
+    GetString(warningName.get(), confirmString);
+
+    const uint32_t buttonFlags =
+        (nsIPrompt::BUTTON_TITLE_IS_STRING * nsIPrompt::BUTTON_POS_0) +
+        (nsIPrompt::BUTTON_TITLE_CANCEL * nsIPrompt::BUTTON_POS_1);
+
+    rv = dialog->ConfirmEx(dialogTitle.get(), confirmString.get(), buttonFlags,
+                           buttonApplyNowText.get(), nullptr, nullptr,
+                           checkboxText.get(), &dontAsk, &buttonPressed);
+    NS_ENSURE_SUCCESS(rv, rv);
+    if (buttonPressed) return NS_ERROR_FAILURE;
+
+    if (dontAsk) prefBranch->SetBoolPref(activePref, false);
+  }
+
+  if (!deleteStorage) {
+    rv = m_folder->MarkMessagesRead(hdrs, true);
+    NS_ENSURE_SUCCESS(rv, rv);
+  }
+
+  if (mDeleteModel != nsMsgImapDeleteModels::IMAPDelete) {
+    m_deletingRows = true;
+  }
+
+  if (m_deletingRows) {
+    mIndicesToNoteChange.AppendElements(selection);
+  }
+
+  rv = m_folder->DeleteMessages(hdrs, window, deleteStorage, false, nullptr,
+                                true /* allow Undo */);
+  if (NS_FAILED(rv)) {
+    m_deletingRows = false;
+  }
+
+  return rv;
+}
+
+nsresult nsMsgDBView::DownloadForOffline(
+    nsIMsgWindow* window, nsTArray<nsMsgViewIndex> const& selection) {
+  nsresult rv = NS_OK;
+  nsTArray<RefPtr<nsIMsgDBHdr>> messages;
+  for (nsMsgViewIndex viewIndex : selection) {
+    nsMsgKey key = m_keys[viewIndex];
+    nsCOMPtr<nsIMsgDBHdr> msgHdr;
+    rv = m_db->GetMsgHdrForKey(key, getter_AddRefs(msgHdr));
+    NS_ENSURE_SUCCESS(rv, rv);
+    if (msgHdr) {
+      uint32_t flags;
+      msgHdr->GetFlags(&flags);
+      if (!(flags & nsMsgMessageFlags::Offline)) {
+        messages.AppendElement(msgHdr);
+      }
+    }
+  }
+
+  m_folder->DownloadMessagesForOffline(messages, window);
+  return rv;
+}
+
+nsresult nsMsgDBView::DownloadFlaggedForOffline(nsIMsgWindow* window) {
+  nsresult rv = NS_OK;
+  nsTArray<RefPtr<nsIMsgDBHdr>> messages;
+  nsCOMPtr<nsIMsgEnumerator> enumerator;
+  rv = GetMessageEnumerator(getter_AddRefs(enumerator));
+  if (NS_SUCCEEDED(rv) && enumerator) {
+    bool hasMore;
+    while (NS_SUCCEEDED(rv = enumerator->HasMoreElements(&hasMore)) &&
+           hasMore) {
+      nsCOMPtr<nsIMsgDBHdr> header;
+      rv = enumerator->GetNext(getter_AddRefs(header));
+      if (header && NS_SUCCEEDED(rv)) {
+        uint32_t flags;
+        header->GetFlags(&flags);
+        if ((flags & nsMsgMessageFlags::Marked) &&
+            !(flags & nsMsgMessageFlags::Offline)) {
+          messages.AppendElement(header);
+        }
+      }
+    }
+  }
+
+  m_folder->DownloadMessagesForOffline(messages, window);
+  return rv;
+}
+
+// Read/unread handling.
+nsresult nsMsgDBView::ToggleReadByIndex(nsMsgViewIndex index) {
+  if (!IsValidIndex(index)) return NS_MSG_INVALID_DBVIEW_INDEX;
+
+  return SetReadByIndex(index, !(m_flags[index] & nsMsgMessageFlags::Read));
+}
+
+nsresult nsMsgDBView::SetReadByIndex(nsMsgViewIndex index, bool read) {
+  nsresult rv;
+
+  if (!IsValidIndex(index)) return NS_MSG_INVALID_DBVIEW_INDEX;
+
+  if (read) {
+    OrExtraFlag(index, nsMsgMessageFlags::Read);
+    // MarkRead() will clear this flag in the db and then call OnKeyChange(),
+    // but because we are the instigator of the change we'll ignore the change.
+    // So we need to clear it in m_flags to keep the db and m_flags in sync.
+    AndExtraFlag(index, ~nsMsgMessageFlags::New);
+  } else {
+    AndExtraFlag(index, ~nsMsgMessageFlags::Read);
+  }
+
+  nsCOMPtr<nsIMsgDatabase> dbToUse;
+  rv = GetDBForViewIndex(index, getter_AddRefs(dbToUse));
+  NS_ENSURE_SUCCESS(rv, rv);
+
+  rv = dbToUse->MarkRead(m_keys[index], read, this);
+  NoteChange(index, 1, nsMsgViewNotificationCode::changed);
+  if (m_viewFlags & nsMsgViewFlagsType::kThreadedDisplay) {
+    nsMsgViewIndex threadIndex = GetThreadIndex(index);
+    if (threadIndex != index)
+      NoteChange(threadIndex, 1, nsMsgViewNotificationCode::changed);
+  }
+
+  return rv;
+}
+
+nsresult nsMsgDBView::SetThreadOfMsgReadByIndex(
+    nsMsgViewIndex index, nsTArray<nsMsgKey>& keysMarkedRead, bool /*read*/) {
+  nsresult rv;
+
+  if (!IsValidIndex(index)) return NS_MSG_INVALID_DBVIEW_INDEX;
+
+  rv = MarkThreadOfMsgRead(m_keys[index], index, keysMarkedRead, true);
+  return rv;
+}
+
+nsresult nsMsgDBView::SetFlaggedByIndex(nsMsgViewIndex index, bool mark) {
+  nsresult rv;
+
+  if (!IsValidIndex(index)) return NS_MSG_INVALID_DBVIEW_INDEX;
+
+  nsCOMPtr<nsIMsgDatabase> dbToUse;
+  rv = GetDBForViewIndex(index, getter_AddRefs(dbToUse));
+  NS_ENSURE_SUCCESS(rv, rv);
+
+  if (mark)
+    OrExtraFlag(index, nsMsgMessageFlags::Marked);
+  else
+    AndExtraFlag(index, ~nsMsgMessageFlags::Marked);
+
+  rv = dbToUse->MarkMarked(m_keys[index], mark, this);
+  NoteChange(index, 1, nsMsgViewNotificationCode::changed);
+  return rv;
+}
+
+nsresult nsMsgDBView::SetMsgHdrJunkStatus(nsIJunkMailPlugin* aJunkPlugin,
+                                          nsIMsgDBHdr* aMsgHdr,
+                                          nsMsgJunkStatus aNewClassification) {
+  // Get the old junk score.
+  nsCString junkScoreStr;
+  nsresult rv = aMsgHdr->GetStringProperty("junkscore", junkScoreStr);
+
+  // And the old origin.
+  nsCString oldOriginStr;
+  rv = aMsgHdr->GetStringProperty("junkscoreorigin", oldOriginStr);
+
+  // If this was not classified by the user, say so.
+  nsMsgJunkStatus oldUserClassification;
+  if (oldOriginStr.get()[0] != 'u') {
+    oldUserClassification = nsIJunkMailPlugin::UNCLASSIFIED;
+  } else {
+    // Otherwise, pass the actual user classification.
+    if (junkScoreStr.IsEmpty())
+      oldUserClassification = nsIJunkMailPlugin::UNCLASSIFIED;
+    else if (junkScoreStr.ToInteger(&rv) == nsIJunkMailPlugin::IS_SPAM_SCORE)
+      oldUserClassification = nsIJunkMailPlugin::JUNK;
+    else
+      oldUserClassification = nsIJunkMailPlugin::GOOD;
+
+    NS_ASSERTION(NS_SUCCEEDED(rv), "Converting junkScore to integer failed.");
+  }
+
+  // Get the URI for this message so we can pass it to the plugin.
+  nsCString uri;
+  nsMsgKey msgKey;
+  nsCOMPtr<nsIMsgFolder> folder;
+  nsCOMPtr<nsIMsgDatabase> db;
+  aMsgHdr->GetMessageKey(&msgKey);
+  rv = aMsgHdr->GetFolder(getter_AddRefs(folder));
+  NS_ENSURE_SUCCESS(rv, rv);
+  GenerateURIForMsgKey(msgKey, folder, uri);
+  NS_ENSURE_SUCCESS(rv, rv);
+  rv = folder->GetMsgDatabase(getter_AddRefs(db));
+  NS_ENSURE_SUCCESS(rv, rv);
+
+  // Tell the plugin about this change, so that it can (potentially)
+  // adjust its database appropriately.
+  nsCOMPtr<nsIMsgWindow> msgWindow(do_QueryReferent(mMsgWindowWeak));
+  rv = aJunkPlugin->SetMessageClassification(
+      uri, oldUserClassification, aNewClassification, msgWindow, this);
+  NS_ENSURE_SUCCESS(rv, rv);
+
+  // This routine is only reached if the user someone touched the UI
+  // and told us the junk status of this message.
+  // Set origin first so that listeners on the junkscore will
+  // know the correct origin.
+  rv = db->SetStringProperty(msgKey, "junkscoreorigin", "user"_ns);
+  NS_ASSERTION(NS_SUCCEEDED(rv), "SetStringPropertyByIndex failed");
+
+  // Set the junk score on the message itself.
+  nsAutoCString msgJunkScore;
+  msgJunkScore.AppendInt(aNewClassification == nsIJunkMailPlugin::JUNK
+                             ? nsIJunkMailPlugin::IS_SPAM_SCORE
+                             : nsIJunkMailPlugin::IS_HAM_SCORE);
+  db->SetStringProperty(msgKey, "junkscore", msgJunkScore);
+  NS_ENSURE_SUCCESS(rv, rv);
+
+  return rv;
+}
+
+nsresult nsMsgDBView::GetFolderFromMsgURI(const nsACString& aMsgURI,
+                                          nsIMsgFolder** aFolder) {
+  NS_IF_ADDREF(*aFolder = m_folder);
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsMsgDBView::OnMessageClassified(const nsACString& aMsgURI,
+                                 nsMsgJunkStatus aClassification,
+                                 uint32_t aJunkPercent)
+
+{
+  // Note: we know all messages in a batch have the same
+  // classification, since unlike OnMessageClassified
+  // methods in other classes (such as nsLocalMailFolder
+  // and nsImapMailFolder), this class, nsMsgDBView, currently
+  // only triggers message classifications due to a command to
+  // mark some of the messages in the view as junk, or as not
+  // junk - so the classification is dictated to the filter,
+  // not suggested by it.
+  //
+  // For this reason the only thing we (may) have to do is
+  // perform the action on all of the junk messages.
+
+  uint32_t numJunk = mJunkHdrs.Length();
+  NS_ASSERTION(aClassification == nsIJunkMailPlugin::GOOD || numJunk,
+               "the classification of a manually-marked junk message has "
+               "been classified as junk, yet there seem to be no such "
+               "outstanding messages");
+
+  // Is this the last message in the batch?
+  if (--mNumMessagesRemainingInBatch == 0 && numJunk > 0) {
+    PerformActionsOnJunkMsgs(aClassification == nsIJunkMailPlugin::JUNK);
+    mJunkHdrs.Clear();
+  }
+
+  return NS_OK;
+}
+
+nsresult nsMsgDBView::PerformActionsOnJunkMsgs(bool msgsAreJunk) {
+  uint32_t numJunkHdrs = mJunkHdrs.Length();
+  if (!numJunkHdrs) {
+    NS_ERROR("no indices of marked-as-junk messages to act on");
+    return NS_OK;
+  }
+
+  nsCOMPtr<nsIMsgFolder> srcFolder;
+  mJunkHdrs[0]->GetFolder(getter_AddRefs(srcFolder));
+
+  bool moveMessages, changeReadState;
+  nsCOMPtr<nsIMsgFolder> targetFolder;
+
+  nsresult rv = DetermineActionsForJunkChange(msgsAreJunk, srcFolder,
+                                              moveMessages, changeReadState,
+                                              getter_AddRefs(targetFolder));
+  NS_ENSURE_SUCCESS(rv, rv);
+
+  // Nothing to do, bail out.
+  if (!(moveMessages || changeReadState)) return NS_OK;
+
+  if (changeReadState) {
+    // Notes on marking junk as read:
+    // 1. There are 2 occasions on which junk messages are marked as
+    //    read: after a manual marking (here and in the front end) and after
+    //    automatic classification by the bayesian filter (see code for local
+    //    mail folders and for imap mail folders). The server-specific
+    //    markAsReadOnSpam pref only applies to the latter, the former is
+    //    controlled by "mailnews.ui.junk.manualMarkAsJunkMarksRead".
+    // 2. Even though move/delete on manual mark may be
+    //    turned off, we might still need to mark as read.
+
+    rv = srcFolder->MarkMessagesRead(mJunkHdrs, msgsAreJunk);
+    NoteChange(0, 0, nsMsgViewNotificationCode::none);
+    NS_ASSERTION(NS_SUCCEEDED(rv),
+                 "marking marked-as-junk messages as read failed");
+  }
+
+  if (moveMessages) {
+    // Check if one of the messages to be junked is actually selected.
+    // If more than one message being junked, one must be selected.
+    // If no tree selection at all, must be in stand-alone message window.
+    bool junkedMsgSelected = numJunkHdrs > 1 || !mTreeSelection;
+    for (nsMsgViewIndex junkIndex = 0;
+         !junkedMsgSelected && junkIndex < numJunkHdrs; junkIndex++) {
+      nsMsgViewIndex hdrIndex = FindHdr(mJunkHdrs[junkIndex]);
+      if (hdrIndex != nsMsgViewIndex_None)
+        mTreeSelection->IsSelected(hdrIndex, &junkedMsgSelected);
+    }
+
+    // If a junked msg is selected, tell the FE to call
+    // SetNextMessageAfterDelete() because a delete is coming.
+    if (junkedMsgSelected) {
+      nsCOMPtr<nsIMsgDBViewCommandUpdater> commandUpdater(
+          do_QueryReferent(mCommandUpdater));
+      if (commandUpdater) {
+        rv = commandUpdater->UpdateNextMessageAfterDelete();
+        NS_ENSURE_SUCCESS(rv, rv);
+      }
+    }
+
+    nsCOMPtr<nsIMsgWindow> msgWindow(do_QueryReferent(mMsgWindowWeak));
+    if (targetFolder) {
+      nsCOMPtr<nsIMsgCopyService> copyService =
+          do_GetService("@mozilla.org/messenger/messagecopyservice;1", &rv);
+      NS_ENSURE_SUCCESS(rv, rv);
+
+      rv = copyService->CopyMessages(srcFolder, mJunkHdrs, targetFolder, true,
+                                     nullptr, msgWindow, true);
+    } else if (msgsAreJunk) {
+      if (mDeleteModel == nsMsgImapDeleteModels::IMAPDelete) {
+        // Unfortunately the DeleteMessages in this case is interpreted by
+        // IMAP as a delete toggle. So what we have to do is to assemble a
+        // new delete array, keeping only those that are not deleted.
+        nsTArray<RefPtr<nsIMsgDBHdr>> hdrsToDelete;
+        for (nsIMsgDBHdr* msgHdr : mJunkHdrs) {
+          if (msgHdr) {
+            uint32_t flags;
+            msgHdr->GetFlags(&flags);
+            if (!(flags & nsMsgMessageFlags::IMAPDeleted)) {
+              hdrsToDelete.AppendElement(msgHdr);
+            }
+          }
+        }
+
+        if (!hdrsToDelete.IsEmpty())
+          rv = srcFolder->DeleteMessages(hdrsToDelete, msgWindow, false, false,
+                                         nullptr, true);
+      } else {
+        rv = srcFolder->DeleteMessages(mJunkHdrs, msgWindow, false, false,
+                                       nullptr, true);
+      }
+    } else if (mDeleteModel == nsMsgImapDeleteModels::IMAPDelete) {
+      nsCOMPtr<nsIMsgImapMailFolder> imapFolder(do_QueryInterface(srcFolder));
+      nsTArray<nsMsgKey> imapUids(numJunkHdrs);
+      for (nsIMsgDBHdr* msgHdr : mJunkHdrs) {
+        nsMsgKey key;
+        msgHdr->GetMessageKey(&key);
+        imapUids.AppendElement(key);
+      }
+
+      imapFolder->StoreImapFlags(kImapMsgDeletedFlag, false, imapUids, nullptr);
+    }
+
+    NoteChange(0, 0, nsMsgViewNotificationCode::none);
+
+    NS_ASSERTION(NS_SUCCEEDED(rv),
+                 "move or deletion of message marked-as-junk/non junk failed");
+  }
+
+  return rv;
+}
+
+nsresult nsMsgDBView::DetermineActionsForJunkChange(
+    bool msgsAreJunk, nsIMsgFolder* srcFolder, bool& moveMessages,
+    bool& changeReadState, nsIMsgFolder** targetFolder) {
+  // There are two possible actions which may be performed
+  // on messages marked as spam: marking as read and moving
+  // somewhere. When a message is marked as non junk,
+  // it may be moved to the inbox, and marked unread.
+  moveMessages = false;
+  changeReadState = false;
+
+  // The 'somewhere', junkTargetFolder, can be a folder,
+  // but if it remains null we'll delete the messages.
+  *targetFolder = nullptr;
+
+  uint32_t folderFlags;
+  srcFolder->GetFlags(&folderFlags);
+
+  nsCOMPtr<nsIMsgIncomingServer> server;
+  nsresult rv = srcFolder->GetServer(getter_AddRefs(server));
+  NS_ENSURE_SUCCESS(rv, rv);
+
+  nsCOMPtr<nsIPrefBranch> prefBranch(
+      do_GetService(NS_PREFSERVICE_CONTRACTID, &rv));
+  NS_ENSURE_SUCCESS(rv, rv);
+
+  // Handle the easy case of marking a junk message as good first.
+  // Set the move target folder to the inbox, if any.
+  if (!msgsAreJunk) {
+    if (folderFlags & nsMsgFolderFlags::Junk) {
+      prefBranch->GetBoolPref("mail.spam.markAsNotJunkMarksUnRead",
+                              &changeReadState);
+      nsCOMPtr<nsIMsgFolder> rootMsgFolder;
+      rv = server->GetRootMsgFolder(getter_AddRefs(rootMsgFolder));
+      NS_ENSURE_SUCCESS(rv, rv);
+      rootMsgFolder->GetFolderWithFlags(nsMsgFolderFlags::Inbox, targetFolder);
+      moveMessages = *targetFolder != nullptr;
+    }
+
+    return NS_OK;
+  }
+
+  nsCOMPtr<nsISpamSettings> spamSettings;
+  rv = server->GetSpamSettings(getter_AddRefs(spamSettings));
+  NS_ENSURE_SUCCESS(rv, rv);
+
+  // When the user explicitly marks a message as junk, we can mark it as read,
+  // too. This is independent of the "markAsReadOnSpam" pref, which applies
+  // only to automatically-classified messages.
+  // Note that this behaviour should match the one in the front end for marking
+  // as junk via toolbar/context menu.
+  prefBranch->GetBoolPref("mailnews.ui.junk.manualMarkAsJunkMarksRead",
+                          &changeReadState);
+
+  // Now let's determine whether we'll be taking the second action,
+  // the move / deletion (and also determine which of these two).
+  bool manualMark;
+  (void)spamSettings->GetManualMark(&manualMark);
+  if (!manualMark) return NS_OK;
+
+  int32_t manualMarkMode;
+  (void)spamSettings->GetManualMarkMode(&manualMarkMode);
+  NS_ASSERTION(manualMarkMode == nsISpamSettings::MANUAL_MARK_MODE_MOVE ||
+                   manualMarkMode == nsISpamSettings::MANUAL_MARK_MODE_DELETE,
+               "bad manual mark mode");
+
+  if (manualMarkMode == nsISpamSettings::MANUAL_MARK_MODE_MOVE) {
+    // If this is a junk folder (not only "the" junk folder for this account)
+    // don't do the move.
+    if (folderFlags & nsMsgFolderFlags::Junk) return NS_OK;
+
+    nsCString spamFolderURI;
+    rv = spamSettings->GetSpamFolderURI(spamFolderURI);
+    NS_ENSURE_SUCCESS(rv, rv);
+
+    NS_ASSERTION(!spamFolderURI.IsEmpty(),
+                 "spam folder URI is empty, can't move");
+    if (!spamFolderURI.IsEmpty()) {
+      rv = FindFolder(spamFolderURI, targetFolder);
+      NS_ENSURE_SUCCESS(rv, rv);
+      if (*targetFolder) {
+        moveMessages = true;
+      } else {
+        // XXX TODO: GetOrCreateJunkFolder will only create a folder with
+        // localized name "Junk" regardless of spamFolderURI. So if someone
+        // sets the junk folder to an existing folder of a different name,
+        // then deletes that folder, this will fail to create the correct
+        // folder.
+        rv = GetOrCreateJunkFolder(spamFolderURI, nullptr /* aListener */);
+        if (NS_SUCCEEDED(rv))
+          rv = GetExistingFolder(spamFolderURI, targetFolder);
+
+        NS_ASSERTION(NS_SUCCEEDED(rv), "GetOrCreateJunkFolder failed");
+      }
+    }
+
+    return NS_OK;
+  }
+
+  // At this point manualMarkMode == nsISpamSettings::MANUAL_MARK_MODE_DELETE).
+
+  // If this is in the trash, let's not delete.
+  if (folderFlags & nsMsgFolderFlags::Trash) return NS_OK;
+
+  return srcFolder->GetCanDeleteMessages(&moveMessages);
+}
+
+// Reversing threads involves reversing the threads but leaving the
+// expanded messages ordered relative to the thread, so we
+// make a copy of each array and copy them over.
+void nsMsgDBView::ReverseThreads() {
+  nsTArray<uint32_t> newFlagArray;
+  nsTArray<nsMsgKey> newKeyArray;
+  nsTArray<uint8_t> newLevelArray;
+
+  uint32_t viewSize = GetSize();
+  uint32_t startThread = viewSize;
+  uint32_t nextThread = viewSize;
+  uint32_t destIndex = 0;
+
+  newKeyArray.SetLength(m_keys.Length());
+  newFlagArray.SetLength(m_flags.Length());
+  newLevelArray.SetLength(m_levels.Length());
+
+  while (startThread) {
+    startThread--;
+
+    if (m_flags[startThread] & MSG_VIEW_FLAG_ISTHREAD) {
+      for (uint32_t sourceIndex = startThread; sourceIndex < nextThread;
+           sourceIndex++) {
+        newKeyArray[destIndex] = m_keys[sourceIndex];
+        newFlagArray[destIndex] = m_flags[sourceIndex];
+        newLevelArray[destIndex] = m_levels[sourceIndex];
+        destIndex++;
+      }
+      // Because we're copying in reverse order.
+      nextThread = startThread;
+    }
+  }
+
+  m_keys.SwapElements(newKeyArray);
+  m_flags.SwapElements(newFlagArray);
+  m_levels.SwapElements(newLevelArray);
+}
+
+void nsMsgDBView::ReverseSort() {
+  uint32_t topIndex = GetSize();
+
+  nsCOMArray<nsIMsgFolder>* folders = GetFolders();
+
+  // Go up half the array swapping values.
+  for (uint32_t bottomIndex = 0; bottomIndex < --topIndex; bottomIndex++) {
+    // Swap flags.
+    uint32_t tempFlags = m_flags[bottomIndex];
+    m_flags[bottomIndex] = m_flags[topIndex];
+    m_flags[topIndex] = tempFlags;
+
+    // Swap keys.
+    nsMsgKey tempKey = m_keys[bottomIndex];
+    m_keys[bottomIndex] = m_keys[topIndex];
+    m_keys[topIndex] = tempKey;
+
+    if (folders) {
+      // Swap folders -- needed when search is done across multiple folders.
+      nsIMsgFolder* bottomFolder = folders->ObjectAt(bottomIndex);
+      nsIMsgFolder* topFolder = folders->ObjectAt(topIndex);
+      folders->ReplaceObjectAt(topFolder, bottomIndex);
+      folders->ReplaceObjectAt(bottomFolder, topIndex);
+    }
+
+    // No need to swap elements in m_levels; since we only call
+    // ReverseSort in non-threaded mode, m_levels are all the same.
+  }
+}
+
+int nsMsgDBView::FnSortIdKey(const IdKey* pItem1, const IdKey* pItem2,
+                             viewSortInfo* sortInfo) {
+  int32_t retVal = 0;
+
+  nsIMsgDatabase* db = sortInfo->db;
+
+  mozilla::DebugOnly<nsresult> rv =
+      db->CompareCollationKeys(pItem1->key, pItem2->key, &retVal);
+  NS_ASSERTION(NS_SUCCEEDED(rv), "compare failed");
+
+  if (retVal) return sortInfo->ascendingSort ? retVal : -retVal;
+
+  return sortInfo->view->SecondaryCompare(pItem1->id, pItem1->folder,
+                                          pItem2->id, pItem2->folder, sortInfo);
+}
+
+int nsMsgDBView::FnSortIdUint32(const IdUint32* pItem1, const IdUint32* pItem2,
+                                viewSortInfo* sortInfo) {
+  if (pItem1->dword > pItem2->dword) {
+    return (sortInfo->ascendingSort) ? 1 : -1;
+  }
+
+  if (pItem1->dword < pItem2->dword) {
+    return (sortInfo->ascendingSort) ? -1 : 1;
+  }
+
+  return sortInfo->view->SecondaryCompare(pItem1->id, pItem1->folder,
+                                          pItem2->id, pItem2->folder, sortInfo);
+}
+
+// XXX are these still correct?
+// To compensate for memory alignment required for systems such as HP-UX, these
+// values must be 4 bytes aligned. Don't break this when modifying the
+// constants.
+const int kMaxSubjectKey = 160;
+const int kMaxLocationKey = 160;  // Also used for account.
+const int kMaxAuthorKey = 160;
+const int kMaxRecipientKey = 80;
+
+// There are cases when pFieldType is not set:
+// one case returns NS_ERROR_UNEXPECTED;
+// the other case now return NS_ERROR_NULL_POINTER (this is only when
+// colHandler below is null, but is very unlikely).
+// The latter case used to return NS_OK, which was incorrect.
+nsresult nsMsgDBView::GetFieldTypeAndLenForSort(
+    nsMsgViewSortTypeValue sortType, uint16_t* pMaxLen, eFieldType* pFieldType,
+    nsIMsgCustomColumnHandler* colHandler) {
+  NS_ENSURE_ARG_POINTER(pMaxLen);
+  NS_ENSURE_ARG_POINTER(pFieldType);
+
+  switch (sortType) {
+    case nsMsgViewSortType::bySubject:
+      *pFieldType = kCollationKey;
+      *pMaxLen = kMaxSubjectKey;
+      break;
+    case nsMsgViewSortType::byAccount:
+    case nsMsgViewSortType::byTags:
+    case nsMsgViewSortType::byLocation:
+      *pFieldType = kCollationKey;
+      *pMaxLen = kMaxLocationKey;
+      break;
+    case nsMsgViewSortType::byRecipient:
+    case nsMsgViewSortType::byCorrespondent:
+      *pFieldType = kCollationKey;
+      *pMaxLen = kMaxRecipientKey;
+      break;
+    case nsMsgViewSortType::byAuthor:
+      *pFieldType = kCollationKey;
+      *pMaxLen = kMaxAuthorKey;
+      break;
+    case nsMsgViewSortType::byDate:
+    case nsMsgViewSortType::byReceived:
+    case nsMsgViewSortType::byPriority:
+    case nsMsgViewSortType::byThread:
+    case nsMsgViewSortType::byId:
+    case nsMsgViewSortType::bySize:
+    case nsMsgViewSortType::byFlagged:
+    case nsMsgViewSortType::byUnread:
+    case nsMsgViewSortType::byStatus:
+    case nsMsgViewSortType::byJunkStatus:
+    case nsMsgViewSortType::byAttachments:
+      *pFieldType = kU32;
+      *pMaxLen = 0;
+      break;
+    case nsMsgViewSortType::byCustom: {
+      if (colHandler == nullptr) {
+        NS_WARNING("colHandler is null. *pFieldType is not set.");
+        return NS_ERROR_NULL_POINTER;
+      }
+
+      bool isString;
+      colHandler->IsString(&isString);
+
+      if (isString) {
+        *pFieldType = kCollationKey;
+        // 80 - do we need a separate k?
+        *pMaxLen = kMaxRecipientKey;
+      } else {
+        *pFieldType = kU32;
+        *pMaxLen = 0;
+      }
+      break;
+    }
+    case nsMsgViewSortType::byNone:
+      // Bug 901948.
+      return NS_ERROR_INVALID_ARG;
+    default: {
+      nsAutoCString message("unexpected switch value: sortType=");
+      message.AppendInt(sortType);
+      NS_WARNING(message.get());
+      return NS_ERROR_UNEXPECTED;
+    }
+  }
+
+  return NS_OK;
+}
+
+#define MSG_STATUS_MASK \
+  (nsMsgMessageFlags::Replied | nsMsgMessageFlags::Forwarded)
+
+nsresult nsMsgDBView::GetStatusSortValue(nsIMsgDBHdr* msgHdr,
+                                         uint32_t* result) {
+  NS_ENSURE_ARG_POINTER(msgHdr);
+  NS_ENSURE_ARG_POINTER(result);
+
+  uint32_t messageFlags;
+  nsresult rv = msgHdr->GetFlags(&messageFlags);
+  NS_ENSURE_SUCCESS(rv, rv);
+
+  if (messageFlags & nsMsgMessageFlags::New) {
+    // Happily, new by definition stands alone.
+    *result = 0;
+    return NS_OK;
+  }
+
+  switch (messageFlags & MSG_STATUS_MASK) {
+    case nsMsgMessageFlags::Replied:
+      *result = 2;
+      break;
+    case nsMsgMessageFlags::Forwarded | nsMsgMessageFlags::Replied:
+      *result = 1;
+      break;
+    case nsMsgMessageFlags::Forwarded:
+      *result = 3;
+      break;
+    default:
+      *result = (messageFlags & nsMsgMessageFlags::Read) ? 4 : 5;
+      break;
+  }
+
+  return NS_OK;
+}
+
+nsresult nsMsgDBView::GetLongField(nsIMsgDBHdr* msgHdr,
+                                   nsMsgViewSortTypeValue sortType,
+                                   uint32_t* result,
+                                   nsIMsgCustomColumnHandler* colHandler) {
+  nsresult rv;
+  NS_ENSURE_ARG_POINTER(msgHdr);
+  NS_ENSURE_ARG_POINTER(result);
+
+  bool isRead;
+  uint32_t bits;
+
+  switch (sortType) {
+    case nsMsgViewSortType::bySize:
+      rv = (mShowSizeInLines) ? msgHdr->GetLineCount(result)
+                              : msgHdr->GetMessageSize(result);
+      break;
+    case nsMsgViewSortType::byPriority:
+      nsMsgPriorityValue priority;
+      rv = msgHdr->GetPriority(&priority);
+      // Treat "none" as "normal" when sorting.
+      if (priority == nsMsgPriority::none) priority = nsMsgPriority::normal;
+
+      // We want highest priority to have lowest value
+      // so ascending sort will have highest priority first.
+      *result = nsMsgPriority::highest - priority;
+      break;
+    case nsMsgViewSortType::byStatus:
+      rv = GetStatusSortValue(msgHdr, result);
+      break;
+    case nsMsgViewSortType::byFlagged:
+      bits = 0;
+      rv = msgHdr->GetFlags(&bits);
+      // Make flagged come out on top.
+      *result = !(bits & nsMsgMessageFlags::Marked);
+      break;
+    case nsMsgViewSortType::byUnread:
+      rv = msgHdr->GetIsRead(&isRead);
+      if (NS_SUCCEEDED(rv)) *result = !isRead;
+
+      break;
+    case nsMsgViewSortType::byJunkStatus: {
+      nsCString junkScoreStr;
+      rv = msgHdr->GetStringProperty("junkscore", junkScoreStr);
+      // Unscored messages should come before messages that are scored
+      // junkScoreStr is "", and "0" - "100"; normalize to 0 - 101.
+      *result = junkScoreStr.IsEmpty() ? (0) : atoi(junkScoreStr.get()) + 1;
+      break;
+    }
+    case nsMsgViewSortType::byAttachments:
+      bits = 0;
+      rv = msgHdr->GetFlags(&bits);
+      *result = !(bits & nsMsgMessageFlags::Attachment);
+      break;
+    case nsMsgViewSortType::byDate:
+      // When sorting threads by date, we may want the date of the newest msg
+      // in the thread.
+      if (m_viewFlags & nsMsgViewFlagsType::kThreadedDisplay &&
+          !(m_viewFlags & nsMsgViewFlagsType::kGroupBySort) &&
+          !mSortThreadsByRoot) {
+        nsCOMPtr<nsIMsgThread> thread;
+        rv = GetThreadContainingMsgHdr(msgHdr, getter_AddRefs(thread));
+        if (NS_SUCCEEDED(rv)) {
+          thread->GetNewestMsgDate(result);
+          break;
+        }
+      }
+      rv = msgHdr->GetDateInSeconds(result);
+      break;
+    case nsMsgViewSortType::byReceived:
+      // When sorting threads by received date, we may want the received date
+      // of the newest msg in the thread.
+      if (m_viewFlags & nsMsgViewFlagsType::kThreadedDisplay &&
+          !(m_viewFlags & nsMsgViewFlagsType::kGroupBySort) &&
+          !mSortThreadsByRoot) {
+        nsCOMPtr<nsIMsgThread> thread;
+        rv = GetThreadContainingMsgHdr(msgHdr, getter_AddRefs(thread));
+        NS_ENSURE_SUCCESS(rv, rv);
+        thread->GetNewestMsgDate(result);
+      } else {
+        // Already in seconds.
+        rv = msgHdr->GetUint32Property("dateReceived", result);
+        if (*result == 0)
+          // Use Date instead, we have no Received property
+          rv = msgHdr->GetDateInSeconds(result);
+      }
+      break;
+    case nsMsgViewSortType::byCustom:
+      if (colHandler != nullptr) {
+        colHandler->GetSortLongForRow(msgHdr, result);
+        rv = NS_OK;
+      } else {
+        NS_ASSERTION(false,
+                     "should not be here (Sort Type: byCustom (Long), but no "
+                     "custom handler)");
+        rv = NS_ERROR_UNEXPECTED;
+      }
+      break;
+    case nsMsgViewSortType::byNone:
+      // Bug 901948.
+      return NS_ERROR_INVALID_ARG;
+
+    case nsMsgViewSortType::byId:
+      // Handled by caller, since caller knows the key.
+    default:
+      NS_ERROR("should not be here");
+      rv = NS_ERROR_UNEXPECTED;
+      break;
+  }
+
+  NS_ENSURE_SUCCESS(rv, rv);
+  return NS_OK;
+}
+
+MsgViewSortColumnInfo::MsgViewSortColumnInfo(
+    const MsgViewSortColumnInfo& other) {
+  mSortType = other.mSortType;
+  mSortOrder = other.mSortOrder;
+  mCustomColumnName = other.mCustomColumnName;
+  mColHandler = other.mColHandler;
+}
+
+bool MsgViewSortColumnInfo::operator==(
+    const MsgViewSortColumnInfo& other) const {
+  return (mSortType == nsMsgViewSortType::byCustom)
+             ? mCustomColumnName.Equals(other.mCustomColumnName)
+             : mSortType == other.mSortType;
+}
+
+nsresult nsMsgDBView::EncodeColumnSort(nsString& columnSortString) {
+  for (uint32_t i = 0; i < m_sortColumns.Length(); i++) {
+    MsgViewSortColumnInfo& sortInfo = m_sortColumns[i];
+    columnSortString.Append((char)sortInfo.mSortType);
+    columnSortString.Append((char)sortInfo.mSortOrder + '0');
+    if (sortInfo.mSortType == nsMsgViewSortType::byCustom) {
+      columnSortString.Append(sortInfo.mCustomColumnName);
+      columnSortString.Append((char16_t)'\r');
+    }
+  }
+
+  return NS_OK;
+}
+
+nsresult nsMsgDBView::DecodeColumnSort(nsString& columnSortString) {
+  const char16_t* stringPtr = columnSortString.BeginReading();
+  while (*stringPtr) {
+    MsgViewSortColumnInfo sortColumnInfo;
+    sortColumnInfo.mSortType = (nsMsgViewSortTypeValue)*stringPtr++;
+    sortColumnInfo.mSortOrder = (nsMsgViewSortOrderValue)(*stringPtr++) - '0';
+    if (sortColumnInfo.mSortType == nsMsgViewSortType::byCustom) {
+      while (*stringPtr && *stringPtr != '\r')
+        sortColumnInfo.mCustomColumnName.Append(*stringPtr++);
+
+      sortColumnInfo.mColHandler =
+          GetColumnHandler(sortColumnInfo.mCustomColumnName);
+
+      // Advance past '\r'.
+      if (*stringPtr) stringPtr++;
+    }
+
+    m_sortColumns.AppendElement(sortColumnInfo);
+  }
+
+  return NS_OK;
+}
+
+//  Secondary Sort Key: when you select a column to sort, that
+//  becomes the new Primary sort key, and all previous sort keys
+//  become secondary. For example, if you first click on Date,
+//  the messages are sorted by Date; then click on From, and now the
+//  messages are sorted by From, and for each value of From the
+//  messages are in Date order.
+
+void nsMsgDBView::PushSort(const MsgViewSortColumnInfo& newSort) {
+  // Handle byNone (bug 901948) ala a mail/base/modules/DBViewerWrapper.jsm
+  // where we don't push the secondary sort type if it's ::byNone;
+  // (and secondary sort type is NOT the same as the first sort type
+  // there). This code should behave the same way.
+
+  // We don't expect to be passed sort type ::byNone,
+  // but if we are it's safe to ignore it.
+  if (newSort.mSortType == nsMsgViewSortType::byNone) return;
+
+  // byId is a unique key (misnamed as Order Received). If we are sorting byId,
+  // we don't need to keep any secondary sort keys.
+  if (newSort.mSortType == nsMsgViewSortType::byId) m_sortColumns.Clear();
+
+  m_sortColumns.RemoveElement(newSort);
+  m_sortColumns.InsertElementAt(0, newSort);
+  if (m_sortColumns.Length() > kMaxNumSortColumns)
+    m_sortColumns.RemoveElementAt(kMaxNumSortColumns);
+}
+
+nsresult nsMsgDBView::GetCollationKey(nsIMsgDBHdr* msgHdr,
+                                      nsMsgViewSortTypeValue sortType,
+                                      nsTArray<uint8_t>& result,
+                                      nsIMsgCustomColumnHandler* colHandler) {
+  nsresult rv = NS_ERROR_UNEXPECTED;
+  NS_ENSURE_ARG_POINTER(msgHdr);
+
+  switch (sortType) {
+    case nsMsgViewSortType::bySubject:
+      rv = msgHdr->GetSubjectCollationKey(result);
+      break;
+    case nsMsgViewSortType::byLocation:
+      rv = GetLocationCollationKey(msgHdr, result);
+      break;
+    case nsMsgViewSortType::byRecipient: {
+      nsString recipients;
+      rv = FetchRecipients(msgHdr, recipients);
+      if (NS_SUCCEEDED(rv)) {
+        nsCOMPtr<nsIMsgDatabase> dbToUse = m_db;
+        // Probably a search view.
+        if (!dbToUse) {
+          rv = GetDBForHeader(msgHdr, getter_AddRefs(dbToUse));
+          NS_ENSURE_SUCCESS(rv, rv);
+        }
+        rv = dbToUse->CreateCollationKey(recipients, result);
+      }
+      break;
+    }
+    case nsMsgViewSortType::byAuthor: {
+      rv = msgHdr->GetAuthorCollationKey(result);
+      nsString author;
+      rv = FetchAuthor(msgHdr, author);
+      if (NS_SUCCEEDED(rv)) {
+        nsCOMPtr<nsIMsgDatabase> dbToUse = m_db;
+        // Probably a search view.
+        if (!dbToUse) {
+          rv = GetDBForHeader(msgHdr, getter_AddRefs(dbToUse));
+          NS_ENSURE_SUCCESS(rv, rv);
+        }
+
+        rv = dbToUse->CreateCollationKey(author, result);
+      }
+      break;
+    }
+    case nsMsgViewSortType::byAccount:
+    case nsMsgViewSortType::byTags: {
+      nsString str;
+      nsCOMPtr<nsIMsgDatabase> dbToUse = m_db;
+
+      if (!dbToUse)
+        // Probably a search view.
+        GetDBForViewIndex(0, getter_AddRefs(dbToUse));
+
+      rv = (sortType == nsMsgViewSortType::byAccount)
+               ? FetchAccount(msgHdr, str)
+               : FetchTags(msgHdr, str);
+      if (NS_SUCCEEDED(rv) && dbToUse)
+        rv = dbToUse->CreateCollationKey(str, result);
+
+      break;
+    }
+    case nsMsgViewSortType::byCustom:
+      if (colHandler != nullptr) {
+        nsAutoString strKey;
+        rv = colHandler->GetSortStringForRow(msgHdr, strKey);
+        NS_ASSERTION(NS_SUCCEEDED(rv),
+                     "failed to get sort string for custom row");
+        nsAutoString strTemp(strKey);
+
+        nsCOMPtr<nsIMsgDatabase> dbToUse = m_db;
+        // Probably a search view.
+        if (!dbToUse) {
+          rv = GetDBForHeader(msgHdr, getter_AddRefs(dbToUse));
+          NS_ENSURE_SUCCESS(rv, rv);
+        }
+        rv = dbToUse->CreateCollationKey(strKey, result);
+      } else {
+        NS_ERROR(
+            "should not be here (Sort Type: byCustom (String), but no custom "
+            "handler)");
+        rv = NS_ERROR_UNEXPECTED;
+      }
+      break;
+    case nsMsgViewSortType::byCorrespondent: {
+      nsString value;
+      if (IsOutgoingMsg(msgHdr))
+        rv = FetchRecipients(msgHdr, value);
+      else
+        rv = FetchAuthor(msgHdr, value);
+
+      if (NS_SUCCEEDED(rv)) {
+        nsCOMPtr<nsIMsgDatabase> dbToUse = m_db;
+        // Probably a search view.
+        if (!dbToUse) {
+          rv = GetDBForHeader(msgHdr, getter_AddRefs(dbToUse));
+          NS_ENSURE_SUCCESS(rv, rv);
+        }
+
+        rv = dbToUse->CreateCollationKey(value, result);
+      }
+      break;
+    }
+    default:
+      rv = NS_ERROR_UNEXPECTED;
+      break;
+  }
+
+  // Bailing out with failure will stop the sort and leave us in
+  // a bad state. Try to continue on, instead.
+  NS_ASSERTION(NS_SUCCEEDED(rv), "failed to get the collation key");
+  if (NS_FAILED(rv)) {
+    result.Clear();
+  }
+
+  return NS_OK;
+}
+
+// As the location collation key is created getting folder from the msgHdr,
+// it is defined in this file and not from the db.
+nsresult nsMsgDBView::GetLocationCollationKey(nsIMsgDBHdr* msgHdr,
+                                              nsTArray<uint8_t>& result) {
+  nsCOMPtr<nsIMsgFolder> folder;
+
+  nsresult rv = msgHdr->GetFolder(getter_AddRefs(folder));
+  NS_ENSURE_SUCCESS(rv, rv);
+  nsCOMPtr<nsIMsgDatabase> dbToUse;
+  rv = folder->GetMsgDatabase(getter_AddRefs(dbToUse));
+  NS_ENSURE_SUCCESS(rv, rv);
+
+  nsString locationString;
+  rv = folder->GetPrettyName(locationString);
+  NS_ENSURE_SUCCESS(rv, rv);
+
+  return dbToUse->CreateCollationKey(locationString, result);
+}
+
+nsresult nsMsgDBView::SaveSortInfo(nsMsgViewSortTypeValue sortType,
+                                   nsMsgViewSortOrderValue sortOrder) {
+  if (m_viewFolder) {
+    nsCOMPtr<nsIDBFolderInfo> folderInfo;
+    nsCOMPtr<nsIMsgDatabase> db;
+    nsresult rv = m_viewFolder->GetDBFolderInfoAndDB(getter_AddRefs(folderInfo),
+                                                     getter_AddRefs(db));
+    if (NS_SUCCEEDED(rv) && folderInfo) {
+      // Save off sort type and order, view type and flags.
+      folderInfo->SetSortType(sortType);
+      folderInfo->SetSortOrder(sortOrder);
+
+      nsString sortColumnsString;
+      rv = EncodeColumnSort(sortColumnsString);
+      NS_ENSURE_SUCCESS(rv, rv);
+      folderInfo->SetProperty("sortColumns", sortColumnsString);
+    }
+  }
+
+  return NS_OK;
+}
+
+nsresult nsMsgDBView::RestoreSortInfo() {
+  if (!m_viewFolder) return NS_OK;
+
+  nsCOMPtr<nsIDBFolderInfo> folderInfo;
+  nsCOMPtr<nsIMsgDatabase> db;
+  nsresult rv = m_viewFolder->GetDBFolderInfoAndDB(getter_AddRefs(folderInfo),
+                                                   getter_AddRefs(db));
+  if (NS_SUCCEEDED(rv) && folderInfo) {
+    // Restore m_sortColumns from db.
+    nsString sortColumnsString;
+    folderInfo->GetProperty("sortColumns", sortColumnsString);
+    DecodeColumnSort(sortColumnsString);
+    if (m_sortColumns.Length() > 1) {
+      m_secondarySort = m_sortColumns[1].mSortType;
+      m_secondarySortOrder = m_sortColumns[1].mSortOrder;
+      m_secondaryCustomColumn = m_sortColumns[1].mCustomColumnName;
+    }
+
+    // Restore curCustomColumn from db.
+    folderInfo->GetProperty("customSortCol", m_curCustomColumn);
+  }
+
+  return NS_OK;
+}
+
+// Called by msgDBView::Sort, at which point any persisted active custom
+// columns must be registered. If not, reset their m_sortColumns entries
+// to byDate; Sort will fill in values if necessary based on new user sort.
+void nsMsgDBView::EnsureCustomColumnsValid() {
+  if (!m_sortColumns.Length()) return;
+
+  for (uint32_t i = 0; i < m_sortColumns.Length(); i++) {
+    if (m_sortColumns[i].mSortType == nsMsgViewSortType::byCustom &&
+        m_sortColumns[i].mColHandler == nullptr) {
+      m_sortColumns[i].mSortType = nsMsgViewSortType::byDate;
+      m_sortColumns[i].mCustomColumnName.Truncate();
+      // There are only two...
+      if (i == 0 && m_sortType != nsMsgViewSortType::byCustom)
+        SetCurCustomColumn(EmptyString());
+      if (i == 1) m_secondaryCustomColumn.Truncate();
+    }
+  }
+}
+
+int32_t nsMsgDBView::SecondaryCompare(nsMsgKey key1, nsIMsgFolder* folder1,
+                                      nsMsgKey key2, nsIMsgFolder* folder2,
+                                      viewSortInfo* comparisonContext) {
+  nsMsgViewSortTypeValue sortType = comparisonContext->view->m_secondarySort;
+  bool isAscendingSort = comparisonContext->view->m_secondarySortOrder ==
+                         nsMsgViewSortOrder::ascending;
+
+  // We need to make sure that in the case of the secondary sort field also
+  // matching, we don't recurse.
+  if (comparisonContext->isSecondarySort ||
+      sortType == nsMsgViewSortType::byId) {
+    if (key1 > key2) {
+      return isAscendingSort ? 1 : -1;
+    }
+
+    if (key1 < key2) {
+      return isAscendingSort ? -1 : 1;
+    }
+
+    return 0;
+  }
+
+  nsCOMPtr<nsIMsgDBHdr> hdr1, hdr2;
+  nsresult rv = folder1->GetMessageHeader(key1, getter_AddRefs(hdr1));
+  NS_ENSURE_SUCCESS(rv, 0);
+  rv = folder2->GetMessageHeader(key2, getter_AddRefs(hdr2));
+  NS_ENSURE_SUCCESS(rv, 0);
+  IdKey EntryInfo1, EntryInfo2;
+
+  uint16_t maxLen;
+  eFieldType fieldType;
+
+  // Get the custom column handler for the *secondary* sort and pass it first
+  // to GetFieldTypeAndLenForSort to get the fieldType and then either
+  // GetCollationKey or GetLongField.
+  nsIMsgCustomColumnHandler* colHandler = nullptr;
+  if (sortType == nsMsgViewSortType::byCustom &&
+      comparisonContext->view->m_sortColumns.Length() > 1) {
+    colHandler = comparisonContext->view->m_sortColumns[1].mColHandler;
+  }
+
+  // The following may leave fieldType undefined.
+  // In this case, we can return 0 right away since
+  // it is the value returned in the default case of
+  // switch (fieldType) statement below.
+  rv = GetFieldTypeAndLenForSort(sortType, &maxLen, &fieldType, colHandler);
+  NS_ENSURE_SUCCESS(rv, 0);
+
+  hdr1->GetMessageKey(&EntryInfo1.id);
+  hdr2->GetMessageKey(&EntryInfo2.id);
+
+  // Set up new viewSortInfo data for our secondary comparison.
+  viewSortInfo ctx = {
+      .view = comparisonContext->view,
+      .db = comparisonContext->db,
+      .isSecondarySort = true,  // To avoid recursing back here!
+      .ascendingSort = isAscendingSort,
+  };
+
+  switch (fieldType) {
+    case kCollationKey:
+      rv = GetCollationKey(hdr1, sortType, EntryInfo1.key, colHandler);
+      NS_ASSERTION(NS_SUCCEEDED(rv), "failed to create collation key");
+      rv = GetCollationKey(hdr2, sortType, EntryInfo2.key, colHandler);
+      NS_ASSERTION(NS_SUCCEEDED(rv), "failed to create collation key");
+
+      return FnSortIdKey(&EntryInfo1, &EntryInfo2, &ctx);
+    case kU32:
+      if (sortType == nsMsgViewSortType::byId) {
+        EntryInfo1.dword = EntryInfo1.id;
+        EntryInfo2.dword = EntryInfo2.id;
+      } else {
+        GetLongField(hdr1, sortType, &EntryInfo1.dword, colHandler);
+        GetLongField(hdr2, sortType, &EntryInfo2.dword, colHandler);
+      }
+      return FnSortIdUint32(&EntryInfo1, &EntryInfo2, &ctx);
+    default:
+      return 0;
+  }
+}
+
+NS_IMETHODIMP nsMsgDBView::Sort(nsMsgViewSortTypeValue sortType,
+                                nsMsgViewSortOrderValue sortOrder) {
+  EnsureCustomColumnsValid();
+
+  // If we're doing a stable sort, we can't just reverse the messages.
+  // Check also that the custom column we're sorting on hasn't changed.
+  // Otherwise, to be on the safe side, resort.
+  // Note: m_curCustomColumn is the desired (possibly new) custom column name,
+  // while m_sortColumns[0].mCustomColumnName is the name for the last completed
+  // sort, since these are persisted after each sort.
+  if (m_sortType == sortType && m_sortValid &&
+      (sortType != nsMsgViewSortType::byCustom ||
+       (sortType == nsMsgViewSortType::byCustom && m_sortColumns.Length() &&
+        m_sortColumns[0].mCustomColumnName.Equals(m_curCustomColumn))) &&
+      m_sortColumns.Length() < 2) {
+    // Same as it ever was. Do nothing.
+    if (m_sortOrder == sortOrder) return NS_OK;
+
+    // For secondary sort, remember the sort order on a per column basis.
+    if (m_sortColumns.Length()) m_sortColumns[0].mSortOrder = sortOrder;
+
+    SaveSortInfo(sortType, sortOrder);
+    if (m_viewFlags & nsMsgViewFlagsType::kThreadedDisplay) {
+      ReverseThreads();
+    } else {
+      ReverseSort();
+    }
+
+    m_sortOrder = sortOrder;
+    // We just reversed the sort order, we still need to invalidate the view.
+    return NS_OK;
+  }
+
+  if (sortType == nsMsgViewSortType::byThread) return NS_OK;
+
+  // If a sortType has changed, or the sortType is byCustom and a column has
+  // changed, this is the new primary sortColumnInfo.
+  // Note: m_curCustomColumn is the desired (possibly new) custom column name,
+  // while m_sortColumns[0].mCustomColumnName is the name for the last completed
+  // sort, since these are persisted after each sort.
+  if (m_sortType != sortType ||
+      (sortType == nsMsgViewSortType::byCustom && m_sortColumns.Length() &&
+       !m_sortColumns[0].mCustomColumnName.Equals(m_curCustomColumn))) {
+    // For secondary sort, remember the sort order of the original primary sort!
+    if (m_sortColumns.Length()) m_sortColumns[0].mSortOrder = m_sortOrder;
+
+    MsgViewSortColumnInfo sortColumnInfo;
+    sortColumnInfo.mSortType = sortType;
+    sortColumnInfo.mSortOrder = sortOrder;
+    if (sortType == nsMsgViewSortType::byCustom) {
+      GetCurCustomColumn(sortColumnInfo.mCustomColumnName);
+      sortColumnInfo.mColHandler = GetCurColumnHandler();
+    }
+
+    PushSort(sortColumnInfo);
+  } else {
+    // For primary sort, remember the sort order on a per column basis.
+    if (m_sortColumns.Length()) m_sortColumns[0].mSortOrder = sortOrder;
+  }
+
+  if (m_sortColumns.Length() > 1) {
+    m_secondarySort = m_sortColumns[1].mSortType;
+    m_secondarySortOrder = m_sortColumns[1].mSortOrder;
+    m_secondaryCustomColumn = m_sortColumns[1].mCustomColumnName;
+  }
+
+  SaveSortInfo(sortType, sortOrder);
+  // Figure out how much memory we'll need, and then malloc it.
+  uint16_t maxLen;
+  eFieldType fieldType;
+
+  // Get the custom column handler for the primary sort and pass it first
+  // to GetFieldTypeAndLenForSort to get the fieldType and then either
+  // GetCollationKey or GetLongField.
+  nsIMsgCustomColumnHandler* colHandler = GetCurColumnHandler();
+
+  // If we did not obtain proper fieldType, it needs to be checked
+  // because the subsequent code does not handle it very well.
+  nsresult rv =
+      GetFieldTypeAndLenForSort(sortType, &maxLen, &fieldType, colHandler);
+
+  // Don't sort if the field type is not supported: Bug 901948.
+  if (NS_FAILED(rv)) return NS_OK;
+
+  nsTArray<void*> ptrs;
+  uint32_t arraySize = GetSize();
+
+  if (!arraySize) return NS_OK;
+
+  nsCOMArray<nsIMsgFolder>* folders = GetFolders();
+  nsCOMPtr<nsIMsgDatabase> dbToUse = m_db;
+  // Probably a search view.
+  if (!dbToUse) {
+    GetDBForViewIndex(0, getter_AddRefs(dbToUse));
+    if (!dbToUse) return NS_ERROR_FAILURE;
+  }
+
+  viewSortInfo qsPrivateData{
+      .view = this,
+      .db = dbToUse,
+      .isSecondarySort = false,
+      .ascendingSort = (sortOrder == nsMsgViewSortOrder::ascending),
+  };
+
+  switch (fieldType) {
+    case kCollationKey: {
+      // Sort on a non-numeric field. We'll be calculating a collation key for
+      // each message.
+      nsTArray<IdKey> entries;
+      entries.SetLength(arraySize);
+      nsTArray<IdKey*> pPtrBase;
+      pPtrBase.SetLength(arraySize);
+      for (uint32_t i = 0; i < arraySize; ++i) {
+        IdKey* info = &entries[i];
+        pPtrBase[i] = info;
+        info->id = m_keys[i];
+        info->bits = m_flags[i];
+        info->dword = 0;
+        info->folder = folders ? folders->ObjectAt(i) : m_folder.get();
+        nsCOMPtr<nsIMsgDBHdr> msgHdr;
+        rv = GetMsgHdrForViewIndex(i, getter_AddRefs(msgHdr));
+        NS_ASSERTION(NS_SUCCEEDED(rv) && msgHdr, "header not found");
+        NS_ENSURE_SUCCESS(rv, rv);
+        rv = GetCollationKey(msgHdr, sortType, info->key, colHandler);
+        NS_ENSURE_SUCCESS(rv, rv);
+      }
+
+      // Perform the sort.
+      std::sort(pPtrBase.begin(), pPtrBase.end(),
+                [&qsPrivateData](const auto& lhs, const auto& rhs) {
+                  return FnSortIdKey(lhs, rhs, &qsPrivateData) < 0;
+                });
+
+      // Now update the view state to reflect the new order.
+      for (uint32_t i = 0; i < arraySize; ++i) {
+        m_keys[i] = pPtrBase[i]->id;
+        m_flags[i] = pPtrBase[i]->bits;
+        if (folders) folders->ReplaceObjectAt(pPtrBase[i]->folder, i);
+      }
+      m_sortType = sortType;
+      m_sortOrder = sortOrder;
+      m_sortValid = true;
+      return NS_OK;
+    }
+    case kU32: {
+      // Sort on a numeric field.
+      nsTArray<IdUint32> entries;
+      entries.SetLength(arraySize);
+      nsTArray<IdUint32*> pPtrBase;
+      pPtrBase.SetLength(arraySize);
+      for (uint32_t i = 0; i < arraySize; ++i) {
+        IdUint32* info = &entries[i];
+        pPtrBase[i] = info;
+        info->id = m_keys[i];
+        info->bits = m_flags[i];
+        info->folder = folders ? folders->ObjectAt(i) : m_folder.get();
+        if (sortType == nsMsgViewSortType::byId) {
+          info->dword = info->id;  // No msgHdr required.
+        } else {
+          nsCOMPtr<nsIMsgDBHdr> msgHdr;
+          rv = GetMsgHdrForViewIndex(i, getter_AddRefs(msgHdr));
+          NS_ASSERTION(NS_SUCCEEDED(rv) && msgHdr, "header not found");
+          NS_ENSURE_SUCCESS(rv, rv);
+          rv = GetLongField(msgHdr, sortType, &info->dword, colHandler);
+          NS_ENSURE_SUCCESS(rv, rv);
+        }
+      }
+
+      // Perform the sort.
+      std::sort(pPtrBase.begin(), pPtrBase.end(),
+                [&qsPrivateData](const auto& lhs, const auto& rhs) {
+                  return FnSortIdUint32(lhs, rhs, &qsPrivateData) < 0;
+                });
+
+      // Now update the view state to reflect the new order.
+      for (uint32_t i = 0; i < arraySize; ++i) {
+        m_keys[i] = pPtrBase[i]->id;
+        m_flags[i] = pPtrBase[i]->bits;
+        if (folders) folders->ReplaceObjectAt(pPtrBase[i]->folder, i);
+      }
+      m_sortType = sortType;
+      m_sortOrder = sortOrder;
+      m_sortValid = true;
+      return NS_OK;
+    }
+    default:
+      // If we get this far, we've got a bad fieldType.
+      return NS_ERROR_UNEXPECTED;
+  }
+}
+
+nsMsgViewIndex nsMsgDBView::GetIndexOfFirstDisplayedKeyInThread(
+    nsIMsgThread* threadHdr, bool allowDummy) {
+  nsMsgViewIndex retIndex = nsMsgViewIndex_None;
+  uint32_t childIndex = 0;
+  // We could speed up the unreadOnly view by starting our search with the first
+  // unread message in the thread. Sometimes, that will be wrong, however, so
+  // let's skip it until we're sure it's necessary.
+  //  (m_viewFlags & nsMsgViewFlagsType::kUnreadOnly)
+  //    ? threadHdr->GetFirstUnreadKey(m_db) : threadHdr->GetChildAt(0);
+  uint32_t numThreadChildren;
+  threadHdr->GetNumChildren(&numThreadChildren);
+  while (retIndex == nsMsgViewIndex_None && childIndex < numThreadChildren) {
+    nsCOMPtr<nsIMsgDBHdr> childHdr;
+    threadHdr->GetChildHdrAt(childIndex++, getter_AddRefs(childHdr));
+    if (childHdr) retIndex = FindHdr(childHdr, 0, allowDummy);
+  }
+
+  return retIndex;
+}
+
+nsresult nsMsgDBView::GetFirstMessageHdrToDisplayInThread(
+    nsIMsgThread* threadHdr, nsIMsgDBHdr** result) {
+  nsresult rv;
+
+  if (m_viewFlags & nsMsgViewFlagsType::kUnreadOnly)
+    rv = threadHdr->GetFirstUnreadChild(result);
+  else
+    rv = threadHdr->GetChildHdrAt(0, result);
+
+  return rv;
+}
+
+// Find the view index of the thread containing the passed msgKey, if
+// the thread is in the view. MsgIndex is passed in as a shortcut if
+// it turns out the msgKey is the first message in the thread,
+// then we can avoid looking for the msgKey.
+nsMsgViewIndex nsMsgDBView::ThreadIndexOfMsg(
+    nsMsgKey msgKey, nsMsgViewIndex msgIndex /* = nsMsgViewIndex_None */,
+    int32_t* pThreadCount /* = NULL */, uint32_t* pFlags /* = NULL */) {
+  if (!(m_viewFlags & nsMsgViewFlagsType::kThreadedDisplay))
+    return nsMsgViewIndex_None;
+
+  nsCOMPtr<nsIMsgDBHdr> msgHdr;
+  nsresult rv = m_db->GetMsgHdrForKey(msgKey, getter_AddRefs(msgHdr));
+  NS_ENSURE_SUCCESS(rv, nsMsgViewIndex_None);
+  return ThreadIndexOfMsgHdr(msgHdr, msgIndex, pThreadCount, pFlags);
+}
+
+nsMsgViewIndex nsMsgDBView::GetThreadIndex(nsMsgViewIndex msgIndex) {
+  if (!IsValidIndex(msgIndex)) return nsMsgViewIndex_None;
+
+  // Scan up looking for level 0 message.
+  while (m_levels[msgIndex] && msgIndex) --msgIndex;
+
+  return msgIndex;
+}
+
+nsMsgViewIndex nsMsgDBView::ThreadIndexOfMsgHdr(nsIMsgDBHdr* msgHdr,
+                                                nsMsgViewIndex msgIndex,
+                                                int32_t* pThreadCount,
+                                                uint32_t* pFlags) {
+  nsCOMPtr<nsIMsgThread> threadHdr;
+  nsresult rv = GetThreadContainingMsgHdr(msgHdr, getter_AddRefs(threadHdr));
+  NS_ENSURE_SUCCESS(rv, nsMsgViewIndex_None);
+
+  nsMsgViewIndex retIndex = nsMsgViewIndex_None;
+
+  if (threadHdr != nullptr) {
+    if (msgIndex == nsMsgViewIndex_None) msgIndex = FindHdr(msgHdr, 0, true);
+
+    // Hdr is not in view, need to find by thread.
+    if (msgIndex == nsMsgViewIndex_None) {
+      msgIndex = GetIndexOfFirstDisplayedKeyInThread(threadHdr, true);
+      // nsMsgKey threadKey = (msgIndex == nsMsgViewIndex_None) ? nsMsgKey_None
+      // :
+      //                                                          GetAt(msgIndex);
+      if (pFlags) threadHdr->GetFlags(pFlags);
+    }
+
+    nsMsgViewIndex startOfThread = msgIndex;
+    while ((int32_t)startOfThread >= 0 && m_levels[startOfThread] != 0)
+      startOfThread--;
+
+    retIndex = startOfThread;
+    if (pThreadCount) {
+      int32_t numChildren = 0;
+      nsMsgViewIndex threadIndex = startOfThread;
+      do {
+        threadIndex++;
+        numChildren++;
+      } while (threadIndex < m_levels.Length() && m_levels[threadIndex] != 0);
+
+      *pThreadCount = numChildren;
+    }
+  }
+
+  return retIndex;
+}
+
+nsMsgKey nsMsgDBView::GetKeyOfFirstMsgInThread(nsMsgKey key) {
+  // Just report no key for any failure. This can occur when a
+  // message is deleted from a threaded view.
+  nsCOMPtr<nsIMsgThread> pThread;
+  nsCOMPtr<nsIMsgDBHdr> msgHdr;
+  nsresult rv = m_db->GetMsgHdrForKey(key, getter_AddRefs(msgHdr));
+  if (NS_FAILED(rv)) return nsMsgKey_None;
+
+  rv = GetThreadContainingMsgHdr(msgHdr, getter_AddRefs(pThread));
+  if (NS_FAILED(rv)) return nsMsgKey_None;
+
+  nsMsgKey firstKeyInThread = nsMsgKey_None;
+
+  if (!pThread) return firstKeyInThread;
+
+  // ### dmb UnreadOnly - this is wrong. But didn't seem to matter in 4.x
+  pThread->GetChildKeyAt(0, &firstKeyInThread);
+  return firstKeyInThread;
+}
+
+NS_IMETHODIMP
+nsMsgDBView::GetKeyAt(nsMsgViewIndex index, nsMsgKey* result) {
+  NS_ENSURE_ARG(result);
+  *result = GetAt(index);
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsMsgDBView::GetFlagsAt(nsMsgViewIndex aIndex, uint32_t* aResult) {
+  NS_ENSURE_ARG(aResult);
+  if (!IsValidIndex(aIndex)) return NS_MSG_INVALID_DBVIEW_INDEX;
+
+  *aResult = m_flags[aIndex];
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsMsgDBView::GetMsgHdrAt(nsMsgViewIndex aIndex, nsIMsgDBHdr** aResult) {
+  NS_ENSURE_ARG(aResult);
+  if (!IsValidIndex(aIndex)) return NS_MSG_INVALID_DBVIEW_INDEX;
+
+  return GetMsgHdrForViewIndex(aIndex, aResult);
+}
+
+nsMsgViewIndex nsMsgDBView::FindHdr(nsIMsgDBHdr* msgHdr,
+                                    nsMsgViewIndex startIndex,
+                                    bool allowDummy) {
+  nsMsgKey msgKey;
+  msgHdr->GetMessageKey(&msgKey);
+  nsMsgViewIndex viewIndex = m_keys.IndexOf(msgKey, startIndex);
+  if (viewIndex == nsMsgViewIndex_None) return viewIndex;
+
+  // If we're supposed to allow dummies, and the previous index is a dummy that
+  // is not elided, then it must be the dummy corresponding to our node and
+  // we should return that instead.
+  if (allowDummy && viewIndex &&
+      (m_flags[viewIndex - 1] & MSG_VIEW_FLAG_DUMMY) &&
+      !(m_flags[viewIndex - 1] & nsMsgMessageFlags::Elided)) {
+    viewIndex--;
+  } else if (!allowDummy && m_flags[viewIndex] & MSG_VIEW_FLAG_DUMMY) {
+    // We're not allowing dummies, and we found a dummy, look again
+    // one past the dummy.
+    return m_keys.IndexOf(msgKey, viewIndex + 1);
+  }
+
+  // Check that the message we found matches the message we were looking for.
+  if (viewIndex != nsMsgViewIndex_None) {
+    nsCOMPtr<nsIMsgDBHdr> foundMsgHdr;
+    nsresult rv = GetMsgHdrForViewIndex(viewIndex, getter_AddRefs(foundMsgHdr));
+    if (NS_FAILED(rv) || foundMsgHdr != msgHdr) {
+      viewIndex = nsMsgViewIndex_None;
+    }
+  }
+
+  return viewIndex;
+}
+
+nsMsgViewIndex nsMsgDBView::FindKey(nsMsgKey key, bool expand) {
+  nsMsgViewIndex retIndex = nsMsgViewIndex_None;
+  retIndex = (nsMsgViewIndex)(m_keys.IndexOf(key));
+  // For dummy headers, try to expand if the caller says so. And if the thread
+  // is expanded, ignore the dummy header and return the real header index.
+  if (retIndex != nsMsgViewIndex_None &&
+      m_flags[retIndex] & MSG_VIEW_FLAG_DUMMY &&
+      !(m_flags[retIndex] & nsMsgMessageFlags::Elided)) {
+    return (nsMsgViewIndex)m_keys.IndexOf(key, retIndex + 1);
+  }
+
+  if (key != nsMsgKey_None &&
+      (retIndex == nsMsgViewIndex_None ||
+       m_flags[retIndex] & MSG_VIEW_FLAG_DUMMY) &&
+      expand && m_db) {
+    nsMsgKey threadKey = GetKeyOfFirstMsgInThread(key);
+    if (threadKey != nsMsgKey_None) {
+      nsMsgViewIndex threadIndex = FindKey(threadKey, false);
+      if (threadIndex != nsMsgViewIndex_None) {
+        uint32_t flags = m_flags[threadIndex];
+        if ((flags & nsMsgMessageFlags::Elided &&
+             NS_SUCCEEDED(ExpandByIndex(threadIndex, nullptr))) ||
+            flags & MSG_VIEW_FLAG_DUMMY) {
+          retIndex = (nsMsgViewIndex)m_keys.IndexOf(key, threadIndex + 1);
+        }
+      }
+    }
+  }
+
+  return retIndex;
+}
+
+nsresult nsMsgDBView::GetThreadCount(nsMsgViewIndex index,
+                                     uint32_t* pThreadCount) {
+  nsCOMPtr<nsIMsgDBHdr> msgHdr;
+  nsresult rv = GetMsgHdrForViewIndex(index, getter_AddRefs(msgHdr));
+  NS_ENSURE_SUCCESS(rv, rv);
+  nsCOMPtr<nsIMsgThread> pThread;
+  rv = GetThreadContainingMsgHdr(msgHdr, getter_AddRefs(pThread));
+  if (NS_SUCCEEDED(rv) && pThread != nullptr)
+    rv = pThread->GetNumChildren(pThreadCount);
+
+  return rv;
+}
+
+// This counts the number of messages in an expanded thread, given the
+// index of the first message in the thread.
+int32_t nsMsgDBView::CountExpandedThread(nsMsgViewIndex index) {
+  int32_t numInThread = 0;
+  nsMsgViewIndex startOfThread = index;
+  while ((int32_t)startOfThread >= 0 && m_levels[startOfThread] != 0)
+    startOfThread--;
+
+  nsMsgViewIndex threadIndex = startOfThread;
+  do {
+    threadIndex++;
+    numInThread++;
+  } while (threadIndex < m_levels.Length() && m_levels[threadIndex] != 0);
+
+  return numInThread;
+}
+
+// Returns the number of lines that would be added (> 0) or removed (< 0)
+// if we were to try to expand/collapse the passed index.
+nsresult nsMsgDBView::ExpansionDelta(nsMsgViewIndex index,
+                                     int32_t* expansionDelta) {
+  uint32_t numChildren;
+  nsresult rv;
+
+  *expansionDelta = 0;
+  if (index >= ((nsMsgViewIndex)m_keys.Length()))
+    return NS_MSG_MESSAGE_NOT_FOUND;
+
+  char flags = m_flags[index];
+
+  if (!(m_viewFlags & nsMsgViewFlagsType::kThreadedDisplay)) return NS_OK;
+
+  // The client can pass in the key of any message
+  // in a thread and get the expansion delta for the thread.
+
+  if (flags & nsMsgMessageFlags::Elided) {
+    rv = GetThreadCount(index, &numChildren);
+    NS_ENSURE_SUCCESS(rv, rv);
+    *expansionDelta = numChildren - 1;
+  } else {
+    numChildren = CountExpandedThread(index);
+    *expansionDelta = -(int32_t)(numChildren - 1);
+  }
+
+  return NS_OK;
+}
+
+nsresult nsMsgDBView::ToggleExpansion(nsMsgViewIndex index,
+                                      uint32_t* numChanged) {
+  nsresult rv;
+  NS_ENSURE_ARG(numChanged);
+  *numChanged = 0;
+  nsMsgViewIndex threadIndex = GetThreadIndex(index);
+  if (threadIndex == nsMsgViewIndex_None) {
+    NS_ASSERTION(false, "couldn't find thread");
+    return NS_MSG_MESSAGE_NOT_FOUND;
+  }
+
+  int32_t flags = m_flags[threadIndex];
+
+  // If not a thread, or doesn't have children, no expand/collapse.
+  // If we add sub-thread expand collapse, this will need to be relaxed.
+  if (!(flags & MSG_VIEW_FLAG_ISTHREAD) || !(flags & MSG_VIEW_FLAG_HASCHILDREN))
+    return NS_MSG_MESSAGE_NOT_FOUND;
+
+  if (flags & nsMsgMessageFlags::Elided)
+    rv = ExpandByIndex(threadIndex, numChanged);
+  else
+    rv = CollapseByIndex(threadIndex, numChanged);
+
+  // If we collaps/uncollapse a thread, this changes the selected URIs.
+  SelectionChangedXPCOM();
+  return rv;
+}
+
+nsresult nsMsgDBView::ExpandAndSelectThread() {
+  nsresult rv;
+
+  NS_ASSERTION(mTreeSelection, "no tree selection");
+  if (!mTreeSelection) return NS_ERROR_UNEXPECTED;
+
+  int32_t index;
+  rv = mTreeSelection->GetCurrentIndex(&index);
+  NS_ENSURE_SUCCESS(rv, rv);
+
+  rv = ExpandAndSelectThreadByIndex(index, false);
+  NS_ENSURE_SUCCESS(rv, rv);
+  return NS_OK;
+}
+
+nsresult nsMsgDBView::ExpandAndSelectThreadByIndex(nsMsgViewIndex index,
+                                                   bool augment) {
+  if (!IsValidIndex(index)) return NS_MSG_INVALID_DBVIEW_INDEX;
+
+  nsresult rv;
+
+  nsMsgViewIndex threadIndex;
+  bool inThreadedMode = (m_viewFlags & nsMsgViewFlagsType::kThreadedDisplay);
+
+  if (inThreadedMode) {
+    nsCOMPtr<nsIMsgDBHdr> msgHdr;
+    rv = GetMsgHdrForViewIndex(index, getter_AddRefs(msgHdr));
+    NS_ENSURE_SUCCESS(rv, rv);
+    threadIndex = ThreadIndexOfMsgHdr(msgHdr, index);
+    if (threadIndex == nsMsgViewIndex_None) {
+      NS_ASSERTION(false, "couldn't find thread");
+      return NS_MSG_MESSAGE_NOT_FOUND;
+    }
+  } else {
+    threadIndex = index;
+  }
+
+  int32_t flags = m_flags[threadIndex];
+  int32_t count = 0;
+
+  if (inThreadedMode && flags & MSG_VIEW_FLAG_ISTHREAD &&
+      flags & MSG_VIEW_FLAG_HASCHILDREN) {
+    // If closed, expand this thread.
+    if (flags & nsMsgMessageFlags::Elided) {
+      uint32_t numExpanded;
+      rv = ExpandByIndex(threadIndex, &numExpanded);
+      NS_ENSURE_SUCCESS(rv, rv);
+    }
+
+    // Get the number of messages in the expanded thread so we know how many
+    // to select.
+    count = CountExpandedThread(threadIndex);
+  } else {
+    count = 1;
+  }
+
+  NS_ASSERTION(count > 0, "bad count");
+
+  // Update the selection.
+
+  NS_ASSERTION(mTreeSelection, "no tree selection");
+  if (!mTreeSelection) return NS_ERROR_UNEXPECTED;
+
+  // The count should be 1 or greater. If there was only one message in the
+  // thread, we just select it. If more, we select all of them.
+  mTreeSelection->RangedSelect(threadIndex + count - 1, threadIndex, augment);
+  return NS_OK;
+}
+
+nsresult nsMsgDBView::ExpandAll() {
+  if (mTree) mTree->BeginUpdateBatch();
+  if (mJSTree) mJSTree->BeginUpdateBatch();
+
+  for (int32_t i = GetSize() - 1; i >= 0; i--) {
+    uint32_t numExpanded;
+    uint32_t flags = m_flags[i];
+    if (flags & nsMsgMessageFlags::Elided) ExpandByIndex(i, &numExpanded);
+  }
+
+  if (mTree) mTree->EndUpdateBatch();
+  if (mJSTree) mJSTree->EndUpdateBatch();
+
+  SelectionChangedXPCOM();
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsMsgDBView::GetThreadContainingMsgHdr(nsIMsgDBHdr* msgHdr,
+                                       nsIMsgThread** pThread) {
+  NS_ENSURE_ARG_POINTER(msgHdr);
+  NS_ENSURE_ARG_POINTER(pThread);
+  if (!m_db) return NS_ERROR_FAILURE;
+  return m_db->GetThreadContainingMsgHdr(msgHdr, pThread);
+}
+
+nsresult nsMsgDBView::ExpandByIndex(nsMsgViewIndex index,
+                                    uint32_t* pNumExpanded) {
+  if ((uint32_t)index >= m_keys.Length()) return NS_MSG_MESSAGE_NOT_FOUND;
+
+  uint32_t flags = m_flags[index];
+  uint32_t numExpanded = 0;
+
+  NS_ASSERTION(flags & nsMsgMessageFlags::Elided,
+               "can't expand an already expanded thread");
+  flags &= ~nsMsgMessageFlags::Elided;
+
+  nsCOMPtr<nsIMsgDBHdr> msgHdr;
+  nsCOMPtr<nsIMsgThread> pThread;
+  nsresult rv = GetThreadContainingIndex(index, getter_AddRefs(pThread));
+  NS_ENSURE_SUCCESS(rv, rv);
+  if (m_viewFlags & nsMsgViewFlagsType::kUnreadOnly) {
+    // Keep top level hdr in thread, even though read.
+    if (flags & nsMsgMessageFlags::Read) {
+      m_levels.AppendElement(0);
+    }
+
+    rv = ListUnreadIdsInThread(pThread, index, &numExpanded);
+  } else {
+    rv = ListIdsInThread(pThread, index, &numExpanded);
+  }
+
+  if (numExpanded > 0) {
+    m_flags[index] = flags;
+    NoteChange(index, 1, nsMsgViewNotificationCode::changed);
+  }
+
+  NoteChange(index + 1, numExpanded, nsMsgViewNotificationCode::insertOrDelete);
+
+  if (pNumExpanded != nullptr) *pNumExpanded = numExpanded;
+
+  return rv;
+}
+
+nsresult nsMsgDBView::CollapseAll() {
+  if (mJSTree) mJSTree->BeginUpdateBatch();
+  for (uint32_t i = 0; i < GetSize(); i++) {
+    uint32_t numExpanded;
+    uint32_t flags = m_flags[i];
+    if (!(flags & nsMsgMessageFlags::Elided) &&
+        (flags & MSG_VIEW_FLAG_HASCHILDREN))
+      CollapseByIndex(i, &numExpanded);
+  }
+
+  if (mJSTree) mJSTree->EndUpdateBatch();
+  SelectionChangedXPCOM();
+  return NS_OK;
+}
+
+nsresult nsMsgDBView::CollapseByIndex(nsMsgViewIndex index,
+                                      uint32_t* pNumCollapsed) {
+  nsresult rv;
+  int32_t flags = m_flags[index];
+  int32_t rowDelta = 0;
+
+  if (flags & nsMsgMessageFlags::Elided ||
+      !(m_viewFlags & nsMsgViewFlagsType::kThreadedDisplay) ||
+      !(flags & MSG_VIEW_FLAG_HASCHILDREN)) {
+    return NS_OK;
+  }
+
+  if (index > m_keys.Length()) return NS_MSG_MESSAGE_NOT_FOUND;
+
+  rv = ExpansionDelta(index, &rowDelta);
+  NS_ENSURE_SUCCESS(rv, rv);
+
+  flags |= nsMsgMessageFlags::Elided;
+
+  m_flags[index] = flags;
+  NoteChange(index, 1, nsMsgViewNotificationCode::changed);
+
+  // Don't count first header in thread.
+  int32_t numRemoved = -rowDelta;
+  if (index + 1 + numRemoved > m_keys.Length()) {
+    NS_ERROR("trying to remove too many rows");
+    numRemoved -= (index + 1 + numRemoved) - m_keys.Length();
+    if (numRemoved <= 0) return NS_MSG_MESSAGE_NOT_FOUND;
+  }
+
+  // Start at first id after thread.
+  RemoveRows(index + 1, numRemoved);
+  if (pNumCollapsed != nullptr) *pNumCollapsed = numRemoved;
+
+  NoteChange(index + 1, rowDelta, nsMsgViewNotificationCode::insertOrDelete);
+
+  return rv;
+}
+
+nsresult nsMsgDBView::OnNewHeader(nsIMsgDBHdr* newHdr, nsMsgKey aParentKey,
+                                  bool /*ensureListed*/) {
+  nsresult rv = NS_OK;
+  // Views can override this behaviour, which is to append to view.
+  // This is the mail behaviour, but threaded views will want
+  // to insert in order...
+  if (newHdr) rv = AddHdr(newHdr);
+
+  return rv;
+}
+
+NS_IMETHODIMP
+nsMsgDBView::GetThreadContainingIndex(nsMsgViewIndex index,
+                                      nsIMsgThread** resultThread) {
+  nsCOMPtr<nsIMsgDBHdr> msgHdr;
+  nsresult rv = GetMsgHdrForViewIndex(index, getter_AddRefs(msgHdr));
+  NS_ENSURE_SUCCESS(rv, rv);
+  return GetThreadContainingMsgHdr(msgHdr, resultThread);
+}
+
+nsMsgViewIndex nsMsgDBView::GetIndexForThread(nsIMsgDBHdr* msgHdr) {
+  // Take advantage of the fact that we're already sorted
+  // and find the insert index via a binary search, though expanded threads
+  // make that tricky.
+
+  nsMsgViewIndex highIndex = m_keys.Length();
+  nsMsgViewIndex lowIndex = 0;
+  IdKey EntryInfo1, EntryInfo2;
+
+  nsresult rv;
+  uint16_t maxLen;
+  eFieldType fieldType;
+
+  // Get the custom column handler for the primary sort and pass it first
+  // to GetFieldTypeAndLenForSort to get the fieldType and then either
+  // GetCollationKey or GetLongField.
+  nsIMsgCustomColumnHandler* colHandler = GetCurColumnHandler();
+
+  // The following may leave fieldType undefined.
+  // In this case, we can return highIndex right away since
+  // it is the value returned in the default case of
+  // switch (fieldType) statement below.
+  rv = GetFieldTypeAndLenForSort(m_sortType, &maxLen, &fieldType, colHandler);
+  NS_ENSURE_SUCCESS(rv, highIndex);
+
+  int retStatus = 0;
+  msgHdr->GetMessageKey(&EntryInfo1.id);
+  msgHdr->GetFolder(&EntryInfo1.folder);
+  EntryInfo1.folder->Release();
+
+  viewSortInfo comparisonContext{
+      .view = this,
+      .isSecondarySort = false,
+      .ascendingSort = (m_sortOrder == nsMsgViewSortOrder::ascending),
+  };
+
+  nsCOMPtr<nsIMsgDatabase> hdrDB;
+  EntryInfo1.folder->GetMsgDatabase(getter_AddRefs(hdrDB));
+  comparisonContext.db = hdrDB.get();
+  switch (fieldType) {
+    case kCollationKey:
+      rv = GetCollationKey(msgHdr, m_sortType, EntryInfo1.key, colHandler);
+      NS_ASSERTION(NS_SUCCEEDED(rv), "failed to create collation key");
+      break;
+    case kU32:
+      if (m_sortType == nsMsgViewSortType::byId) {
+        EntryInfo1.dword = EntryInfo1.id;
+      } else {
+        GetLongField(msgHdr, m_sortType, &EntryInfo1.dword, colHandler);
+      }
+
+      break;
+    default:
+      return highIndex;
+  }
+
+  while (highIndex > lowIndex) {
+    nsMsgViewIndex tryIndex = (lowIndex + highIndex) / 2;
+    // Need to adjust tryIndex if it's not a thread.
+    while (m_levels[tryIndex] && tryIndex) tryIndex--;
+
+    if (tryIndex < lowIndex) {
+      NS_ERROR("try index shouldn't be less than low index");
+      break;
+    }
+
+    EntryInfo2.id = m_keys[tryIndex];
+    GetFolderForViewIndex(tryIndex, &EntryInfo2.folder);
+    EntryInfo2.folder->Release();
+
+    nsCOMPtr<nsIMsgDBHdr> tryHdr;
+    nsCOMPtr<nsIMsgDatabase> db;
+    // ### this should get the db from the folder...
+    GetDBForViewIndex(tryIndex, getter_AddRefs(db));
+    if (db) db->GetMsgHdrForKey(EntryInfo2.id, getter_AddRefs(tryHdr));
+
+    if (!tryHdr) break;
+
+    if (tryHdr == msgHdr) {
+      NS_WARNING("didn't expect header to already be in view");
+      highIndex = tryIndex;
+      break;
+    }
+
+    if (fieldType == kCollationKey) {
+      rv = GetCollationKey(tryHdr, m_sortType, EntryInfo2.key, colHandler);
+      NS_ASSERTION(NS_SUCCEEDED(rv), "failed to create collation key");
+
+      retStatus = FnSortIdKey(&EntryInfo1, &EntryInfo2, &comparisonContext);
+    } else if (fieldType == kU32) {
+      if (m_sortType == nsMsgViewSortType::byId) {
+        EntryInfo2.dword = EntryInfo2.id;
+      } else {
+        GetLongField(tryHdr, m_sortType, &EntryInfo2.dword, colHandler);
+      }
+
+      retStatus = FnSortIdUint32(&EntryInfo1, &EntryInfo2, &comparisonContext);
+    }
+
+    if (retStatus == 0) {
+      highIndex = tryIndex;
+      break;
+    }
+
+    if (retStatus < 0) {
+      highIndex = tryIndex;
+      // We already made sure tryIndex was at a thread at the top of the loop.
+    } else {
+      lowIndex = tryIndex + 1;
+      while (lowIndex < GetSize() && m_levels[lowIndex]) lowIndex++;
+    }
+  }
+
+  return highIndex;
+}
+
+nsMsgViewIndex nsMsgDBView::GetInsertIndexHelper(
+    nsIMsgDBHdr* msgHdr, nsTArray<nsMsgKey>& keys,
+    nsCOMArray<nsIMsgFolder>* folders, nsMsgViewSortOrderValue sortOrder,
+    nsMsgViewSortTypeValue sortType) {
+  nsMsgViewIndex highIndex = keys.Length();
+  nsMsgViewIndex lowIndex = 0;
+  IdKey EntryInfo1, EntryInfo2;
+
+  nsresult rv;
+  uint16_t maxLen;
+  eFieldType fieldType;
+
+  // Get the custom column handler for the primary sort and pass it first
+  // to GetFieldTypeAndLenForSort to get the fieldType and then either
+  // GetCollationKey or GetLongField.
+  nsIMsgCustomColumnHandler* colHandler = GetCurColumnHandler();
+
+  // The following may leave fieldType undefined.
+  // In this case, we can return highIndex right away since
+  // it is the value returned in the default case of
+  // switch (fieldType) statement below.
+  rv = GetFieldTypeAndLenForSort(sortType, &maxLen, &fieldType, colHandler);
+  NS_ENSURE_SUCCESS(rv, highIndex);
+
+  int retStatus = 0;
+  msgHdr->GetMessageKey(&EntryInfo1.id);
+  msgHdr->GetFolder(&EntryInfo1.folder);
+  EntryInfo1.folder->Release();
+
+  viewSortInfo comparisonContext{
+      .view = this,
+      .isSecondarySort = false,
+      .ascendingSort = (sortOrder == nsMsgViewSortOrder::ascending),
+  };
+
+  rv = EntryInfo1.folder->GetMsgDatabase(&comparisonContext.db);
+  NS_ENSURE_SUCCESS(rv, highIndex);
+  comparisonContext.db->Release();
+
+  switch (fieldType) {
+    case kCollationKey:
+      rv = GetCollationKey(msgHdr, sortType, EntryInfo1.key, colHandler);
+      NS_ASSERTION(NS_SUCCEEDED(rv), "failed to create collation key");
+      break;
+    case kU32:
+      if (sortType == nsMsgViewSortType::byId) {
+        EntryInfo1.dword = EntryInfo1.id;
+      } else {
+        GetLongField(msgHdr, sortType, &EntryInfo1.dword, colHandler);
+      }
+
+      break;
+    default:
+      return highIndex;
+  }
+
+  while (highIndex > lowIndex) {
+    nsMsgViewIndex tryIndex = (lowIndex + highIndex - 1) / 2;
+    EntryInfo2.id = keys[tryIndex];
+    EntryInfo2.folder = folders ? folders->ObjectAt(tryIndex) : m_folder.get();
+
+    nsCOMPtr<nsIMsgDBHdr> tryHdr;
+    EntryInfo2.folder->GetMessageHeader(EntryInfo2.id, getter_AddRefs(tryHdr));
+    if (!tryHdr) break;
+
+    if (fieldType == kCollationKey) {
+      rv = GetCollationKey(tryHdr, sortType, EntryInfo2.key, colHandler);
+      NS_ASSERTION(NS_SUCCEEDED(rv), "failed to create collation key");
+
+      retStatus = FnSortIdKey(&EntryInfo1, &EntryInfo2, &comparisonContext);
+    } else if (fieldType == kU32) {
+      if (sortType == nsMsgViewSortType::byId) {
+        EntryInfo2.dword = EntryInfo2.id;
+      } else {
+        GetLongField(tryHdr, sortType, &EntryInfo2.dword, colHandler);
+      }
+
+      retStatus = FnSortIdUint32(&EntryInfo1, &EntryInfo2, &comparisonContext);
+    }
+
+    if (retStatus == 0) {
+      highIndex = tryIndex;
+      break;
+    }
+
+    if (retStatus < 0) {
+      highIndex = tryIndex;
+    } else {
+      lowIndex = tryIndex + 1;
+    }
+  }
+
+  return highIndex;
+}
+
+nsMsgViewIndex nsMsgDBView::GetInsertIndex(nsIMsgDBHdr* msgHdr) {
+  if (!GetSize()) return 0;
+
+  if ((m_viewFlags & nsMsgViewFlagsType::kThreadedDisplay) != 0 &&
+      !(m_viewFlags & nsMsgViewFlagsType::kGroupBySort) &&
+      m_sortOrder != nsMsgViewSortType::byId) {
+    return GetIndexForThread(msgHdr);
+  }
+
+  return GetInsertIndexHelper(msgHdr, m_keys, GetFolders(), m_sortOrder,
+                              m_sortType);
+}
+
+nsresult nsMsgDBView::AddHdr(nsIMsgDBHdr* msgHdr, nsMsgViewIndex* resultIndex) {
+  uint32_t flags = 0;
+#ifdef DEBUG_bienvenu
+  NS_ASSERTION(m_keys.Length() == m_flags.Length() &&
+                   (int)m_keys.Length() == m_levels.Length(),
+               "view arrays out of sync!");
+#endif
+
+  if (resultIndex) *resultIndex = nsMsgViewIndex_None;
+
+  if (!GetShowingIgnored()) {
+    nsCOMPtr<nsIMsgThread> thread;
+    GetThreadContainingMsgHdr(msgHdr, getter_AddRefs(thread));
+    if (thread) {
+      thread->GetFlags(&flags);
+      if (flags & nsMsgMessageFlags::Ignored) return NS_OK;
+    }
+
+    bool ignored;
+    msgHdr->GetIsKilled(&ignored);
+    if (ignored) return NS_OK;
+  }
+
+  nsMsgKey msgKey, threadId;
+  nsMsgKey threadParent;
+  msgHdr->GetMessageKey(&msgKey);
+  msgHdr->GetThreadId(&threadId);
+  msgHdr->GetThreadParent(&threadParent);
+
+  msgHdr->GetFlags(&flags);
+  // XXX this isn't quite right, is it?
+  // Should be checking that our thread parent key is none?
+  if (threadParent == nsMsgKey_None) flags |= MSG_VIEW_FLAG_ISTHREAD;
+
+  nsMsgViewIndex insertIndex = GetInsertIndex(msgHdr);
+  if (insertIndex == nsMsgViewIndex_None) {
+    // If unreadonly, level is 0 because we must be the only msg in the thread.
+    int32_t levelToAdd = 0;
+
+    if (m_sortOrder == nsMsgViewSortOrder::ascending) {
+      InsertMsgHdrAt(GetSize(), msgHdr, msgKey, flags, levelToAdd);
+      if (resultIndex) *resultIndex = GetSize() - 1;
+
+      // The call to NoteChange() has to happen after we add the key as
+      // NoteChange() will call RowCountChanged() which will call our
+      // GetRowCount().
+      NoteChange(GetSize() - 1, 1, nsMsgViewNotificationCode::insertOrDelete);
+    } else {
+      InsertMsgHdrAt(0, msgHdr, msgKey, flags, levelToAdd);
+      if (resultIndex) *resultIndex = 0;
+
+      // The call to NoteChange() has to happen after we insert the key as
+      // NoteChange() will call RowCountChanged() which will call our
+      // GetRowCount().
+      NoteChange(0, 1, nsMsgViewNotificationCode::insertOrDelete);
+    }
+
+    m_sortValid = false;
+  } else {
+    InsertMsgHdrAt(insertIndex, msgHdr, msgKey, flags, 0);
+    if (resultIndex) *resultIndex = insertIndex;
+
+    // The call to NoteChange() has to happen after we add the key as
+    // NoteChange() will call RowCountChanged() which will call our
+    // GetRowCount().
+    NoteChange(insertIndex, 1, nsMsgViewNotificationCode::insertOrDelete);
+  }
+
+  OnHeaderAddedOrDeleted();
+  return NS_OK;
+}
+
+bool nsMsgDBView::WantsThisThread(nsIMsgThread* /*threadHdr*/) {
+  // Default is to want all threads.
+  return true;
+}
+
+nsMsgViewIndex nsMsgDBView::FindParentInThread(
+    nsMsgKey parentKey, nsMsgViewIndex startOfThreadViewIndex) {
+  nsCOMPtr<nsIMsgDBHdr> msgHdr;
+  while (parentKey != nsMsgKey_None) {
+    nsMsgViewIndex parentIndex =
+        m_keys.IndexOf(parentKey, startOfThreadViewIndex);
+    if (parentIndex != nsMsgViewIndex_None) return parentIndex;
+
+    if (NS_FAILED(m_db->GetMsgHdrForKey(parentKey, getter_AddRefs(msgHdr))))
+      break;
+
+    msgHdr->GetThreadParent(&parentKey);
+  }
+
+  return startOfThreadViewIndex;
+}
+
+nsresult nsMsgDBView::ListIdsInThreadOrder(nsIMsgThread* threadHdr,
+                                           nsMsgKey parentKey, uint32_t level,
+                                           nsMsgViewIndex* viewIndex,
+                                           uint32_t* pNumListed) {
+  nsCOMPtr<nsIMsgEnumerator> msgEnumerator;
+  nsresult rv =
+      threadHdr->EnumerateMessages(parentKey, getter_AddRefs(msgEnumerator));
+  NS_ENSURE_SUCCESS(rv, rv);
+  uint32_t numChildren;
+  (void)threadHdr->GetNumChildren(&numChildren);
+  NS_ASSERTION(numChildren, "Empty thread in view/db");
+  // Bogus, but harmless.
+  if (!numChildren) return NS_OK;
+
+  // Account for the existing thread root.
+  numChildren--;
+
+  // Skip the first one.
+  bool hasMore;
+  while (NS_SUCCEEDED(msgEnumerator->HasMoreElements(&hasMore)) && hasMore) {
+    nsCOMPtr<nsIMsgDBHdr> msgHdr;
+    rv = msgEnumerator->GetNext(getter_AddRefs(msgHdr));
+    NS_ENSURE_SUCCESS(rv, rv);
+    if (*pNumListed == numChildren) {
+      MOZ_ASSERT_UNREACHABLE("thread corrupt in db");
+      // If we've listed more messages than are in the thread, then the db
+      // is corrupt, and we should invalidate it.
+      // We'll use this rv to indicate there's something wrong with the db
+      // though for now it probably won't get paid attention to.
+      m_db->SetSummaryValid(false);
+      return NS_MSG_ERROR_FOLDER_SUMMARY_OUT_OF_DATE;
+    }
+
+    if (!(m_viewFlags & nsMsgViewFlagsType::kShowIgnored)) {
+      bool ignored;
+      msgHdr->GetIsKilled(&ignored);
+      // We are not going to process subthreads, horribly invalidating the
+      // numChildren characteristic.
+      if (ignored) continue;
+    }
+
+    nsMsgKey msgKey;
+    uint32_t msgFlags, newFlags;
+    msgHdr->GetMessageKey(&msgKey);
+    msgHdr->GetFlags(&msgFlags);
+    AdjustReadFlag(msgHdr, &msgFlags);
+    SetMsgHdrAt(msgHdr, *viewIndex, msgKey, msgFlags & ~MSG_VIEW_FLAGS, level);
+    // Turn off thread or elided bit if they got turned on (maybe from new
+    // only view?)
+    msgHdr->AndFlags(~(MSG_VIEW_FLAG_ISTHREAD | nsMsgMessageFlags::Elided),
+                     &newFlags);
+    (*pNumListed)++;
+    (*viewIndex)++;
+    rv = ListIdsInThreadOrder(threadHdr, msgKey, level + 1, viewIndex,
+                              pNumListed);
+    NS_ENSURE_SUCCESS(rv, rv);
+  }
+  return NS_OK;
+}
+
+void nsMsgDBView::InsertEmptyRows(nsMsgViewIndex viewIndex, int32_t numRows) {
+  m_keys.InsertElementsAt(viewIndex, numRows, 0);
+  m_flags.InsertElementsAt(viewIndex, numRows, 0);
+  m_levels.InsertElementsAt(viewIndex, numRows, 1);
+}
+
+void nsMsgDBView::RemoveRows(nsMsgViewIndex viewIndex, int32_t numRows) {
+  m_keys.RemoveElementsAt(viewIndex, numRows);
+  m_flags.RemoveElementsAt(viewIndex, numRows);
+  m_levels.RemoveElementsAt(viewIndex, numRows);
+}
+
+NS_IMETHODIMP
+nsMsgDBView::InsertTreeRows(nsMsgViewIndex aIndex, uint32_t aNumRows,
+                            nsMsgKey aKey, nsMsgViewFlagsTypeValue aFlags,
+                            uint32_t aLevel, nsIMsgFolder* aFolder) {
+  if (GetSize() < aIndex) return NS_ERROR_UNEXPECTED;
+
+  nsCOMArray<nsIMsgFolder>* folders = GetFolders();
+  if (folders) {
+    // In a search/xfvf view only, a folder is required.
+    NS_ENSURE_ARG_POINTER(aFolder);
+    for (size_t i = 0; i < aNumRows; i++)
+      // Insert into m_folders.
+      if (!folders->InsertObjectAt(aFolder, aIndex + i))
+        return NS_ERROR_UNEXPECTED;
+  }
+
+  m_keys.InsertElementsAt(aIndex, aNumRows, aKey);
+  m_flags.InsertElementsAt(aIndex, aNumRows, aFlags);
+  m_levels.InsertElementsAt(aIndex, aNumRows, aLevel);
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsMsgDBView::RemoveTreeRows(nsMsgViewIndex aIndex, uint32_t aNumRows) {
+  // Prevent a crash if attempting to remove rows which don't exist.
+  if (GetSize() < aIndex + aNumRows) return NS_ERROR_UNEXPECTED;
+
+  nsMsgDBView::RemoveRows(aIndex, aNumRows);
+
+  nsCOMArray<nsIMsgFolder>* folders = GetFolders();
+  if (folders)
+    // In a search/xfvf view only, remove from m_folders.
+    if (!folders->RemoveObjectsAt(aIndex, aNumRows)) return NS_ERROR_UNEXPECTED;
+
+  return NS_OK;
+}
+
+nsresult nsMsgDBView::ListIdsInThread(nsIMsgThread* threadHdr,
+                                      nsMsgViewIndex startOfThreadViewIndex,
+                                      uint32_t* pNumListed) {
+  NS_ENSURE_ARG(threadHdr);
+  // These children ids should be in thread order.
+  nsresult rv = NS_OK;
+  uint32_t i;
+  nsMsgViewIndex viewIndex = startOfThreadViewIndex + 1;
+  *pNumListed = 0;
+
+  uint32_t numChildren;
+  threadHdr->GetNumChildren(&numChildren);
+  NS_ASSERTION(numChildren, "Empty thread in view/db");
+  if (!numChildren) return NS_OK;
+
+  // Account for the existing thread root.
+  numChildren--;
+  InsertEmptyRows(viewIndex, numChildren);
+
+  // ### need to rework this when we implemented threading in group views.
+  if (m_viewFlags & nsMsgViewFlagsType::kThreadedDisplay &&
+      !(m_viewFlags & nsMsgViewFlagsType::kGroupBySort)) {
+    nsMsgKey parentKey = m_keys[startOfThreadViewIndex];
+    // If the thread is bigger than the hdr cache, expanding the thread
+    // can be slow. Increasing the hdr cache size will help a fair amount.
+    uint32_t hdrCacheSize;
+    m_db->GetMsgHdrCacheSize(&hdrCacheSize);
+    if (numChildren > hdrCacheSize) m_db->SetMsgHdrCacheSize(numChildren);
+
+    // If this fails, *pNumListed will be 0, and we'll fall back to just
+    // enumerating the messages in the thread below.
+    rv = ListIdsInThreadOrder(threadHdr, parentKey, 1, &viewIndex, pNumListed);
+    if (numChildren > hdrCacheSize) m_db->SetMsgHdrCacheSize(hdrCacheSize);
+  }
+
+  if (!*pNumListed) {
+    uint32_t ignoredHeaders = 0;
+    // If we're not threaded, just list em out in db order.
+    for (i = 1; i <= numChildren; i++) {
+      nsCOMPtr<nsIMsgDBHdr> msgHdr;
+      threadHdr->GetChildHdrAt(i, getter_AddRefs(msgHdr));
+
+      if (msgHdr != nullptr) {
+        if (!(m_viewFlags & nsMsgViewFlagsType::kShowIgnored)) {
+          bool killed;
+          msgHdr->GetIsKilled(&killed);
+          if (killed) {
+            ignoredHeaders++;
+            continue;
+          }
+        }
+
+        nsMsgKey msgKey;
+        uint32_t msgFlags, newFlags;
+        msgHdr->GetMessageKey(&msgKey);
+        msgHdr->GetFlags(&msgFlags);
+        AdjustReadFlag(msgHdr, &msgFlags);
+        SetMsgHdrAt(msgHdr, viewIndex, msgKey, msgFlags & ~MSG_VIEW_FLAGS, 1);
+        // Here, we're either flat, or we're grouped - in either case,
+        // level is 1. Turn off thread or elided bit if they got turned on
+        // (maybe from new only view?).
+        if (i > 0)
+          msgHdr->AndFlags(
+              ~(MSG_VIEW_FLAG_ISTHREAD | nsMsgMessageFlags::Elided), &newFlags);
+
+        (*pNumListed)++;
+        viewIndex++;
+      }
+    }
+
+    if (ignoredHeaders + *pNumListed < numChildren) {
+      MOZ_ASSERT_UNREACHABLE("thread corrupt in db");
+      // If we've listed fewer messages than are in the thread, then the db
+      // is corrupt, and we should invalidate it.
+      // We'll use this rv to indicate there's something wrong with the db
+      // though for now it probably won't get paid attention to.
+      m_db->SetSummaryValid(false);
+      rv = NS_MSG_ERROR_FOLDER_SUMMARY_OUT_OF_DATE;
+    }
+  }
+
+  // We may have added too many elements (i.e., subthreads were cut).
+  // XXX Fix for cross folder view case.
+  if (*pNumListed < numChildren)
+    RemoveRows(viewIndex, numChildren - *pNumListed);
+
+  return rv;
+}
+
+int32_t nsMsgDBView::FindLevelInThread(nsIMsgDBHdr* msgHdr,
+                                       nsMsgViewIndex startOfThread,
+                                       nsMsgViewIndex viewIndex) {
+  nsCOMPtr<nsIMsgDBHdr> curMsgHdr = msgHdr;
+  nsMsgKey msgKey;
+  msgHdr->GetMessageKey(&msgKey);
+
+  // Look through the ancestors of the passed in msgHdr in turn, looking for
+  // them in the view, up to the start of the thread. If we find an ancestor,
+  // then our level is one greater than the level of the ancestor.
+  while (curMsgHdr) {
+    nsMsgKey parentKey;
+    curMsgHdr->GetThreadParent(&parentKey);
+    if (parentKey == nsMsgKey_None) break;
+
+    // Scan up to find view index of ancestor, if any.
+    for (nsMsgViewIndex indexToTry = viewIndex;
+         indexToTry && indexToTry-- >= startOfThread;) {
+      if (m_keys[indexToTry] == parentKey) return m_levels[indexToTry] + 1;
+    }
+
+    // If msgHdr's key is its parentKey, we'll loop forever, so protect
+    // against that corruption.
+    if (msgKey == parentKey || NS_FAILED(m_db->GetMsgHdrForKey(
+                                   parentKey, getter_AddRefs(curMsgHdr)))) {
+      NS_ERROR(
+          "msgKey == parentKey, or GetMsgHdrForKey failed, this used to be an "
+          "infinite loop condition");
+      curMsgHdr = nullptr;
+    } else {
+      // Need to update msgKey so the check for a msgHdr with matching
+      // key+parentKey will work after first time through loop.
+      curMsgHdr->GetMessageKey(&msgKey);
+    }
+  }
+
+  return 1;
+}
+
+// XXX Can this be combined with GetIndexForThread??
+nsMsgViewIndex nsMsgDBView::GetThreadRootIndex(nsIMsgDBHdr* msgHdr) {
+  if (!msgHdr) {
+    NS_WARNING("null msgHdr parameter");
+    return nsMsgViewIndex_None;
+  }
+
+  // Take advantage of the fact that we're already sorted
+  // and find the thread root via a binary search.
+
+  nsMsgViewIndex highIndex = m_keys.Length();
+  nsMsgViewIndex lowIndex = 0;
+  IdKey EntryInfo1, EntryInfo2;
+
+  nsresult rv;
+  uint16_t maxLen;
+  eFieldType fieldType;
+
+  // Get the custom column handler for the primary sort and pass it first
+  // to GetFieldTypeAndLenForSort to get the fieldType and then either
+  // GetCollationKey or GetLongField.
+  nsIMsgCustomColumnHandler* colHandler = GetCurColumnHandler();
+
+  // The following may leave fieldType undefined.
+  // In this case, we can return highIndex right away since
+  // it is the value returned in the default case of
+  // switch (fieldType) statement below.
+  rv = GetFieldTypeAndLenForSort(m_sortType, &maxLen, &fieldType, colHandler);
+  NS_ENSURE_SUCCESS(rv, highIndex);
+
+  int retStatus = 0;
+  msgHdr->GetMessageKey(&EntryInfo1.id);
+  msgHdr->GetFolder(&EntryInfo1.folder);
+  EntryInfo1.folder->Release();
+
+  viewSortInfo comparisonContext{
+      .view = this,
+      .isSecondarySort = false,
+      .ascendingSort = (m_sortOrder == nsMsgViewSortOrder::ascending),
+  };
+
+  nsCOMPtr<nsIMsgDatabase> hdrDB;
+  EntryInfo1.folder->GetMsgDatabase(getter_AddRefs(hdrDB));
+  comparisonContext.db = hdrDB.get();
+
+  switch (fieldType) {
+    case kCollationKey:
+      rv = GetCollationKey(msgHdr, m_sortType, EntryInfo1.key, colHandler);
+      NS_ASSERTION(NS_SUCCEEDED(rv), "failed to create collation key");
+      break;
+    case kU32:
+      if (m_sortType == nsMsgViewSortType::byId) {
+        EntryInfo1.dword = EntryInfo1.id;
+      } else {
+        GetLongField(msgHdr, m_sortType, &EntryInfo1.dword, colHandler);
+      }
+
+      break;
+    default:
+      return highIndex;
+  }
+
+  while (highIndex > lowIndex) {
+    nsMsgViewIndex tryIndex = (lowIndex + highIndex) / 2;
+    // Need to adjust tryIndex if it's not a thread.
+    while (m_levels[tryIndex] && tryIndex) tryIndex--;
+
+    if (tryIndex < lowIndex) {
+      NS_ERROR("try index shouldn't be less than low index");
+      break;
+    }
+
+    EntryInfo2.id = m_keys[tryIndex];
+    GetFolderForViewIndex(tryIndex, &EntryInfo2.folder);
+    EntryInfo2.folder->Release();
+
+    nsCOMPtr<nsIMsgDBHdr> tryHdr;
+    nsCOMPtr<nsIMsgDatabase> db;
+    // ### this should get the db from the folder...
+    GetDBForViewIndex(tryIndex, getter_AddRefs(db));
+    if (db) db->GetMsgHdrForKey(EntryInfo2.id, getter_AddRefs(tryHdr));
+
+    if (!tryHdr) break;
+
+    if (tryHdr == msgHdr) {
+      highIndex = tryIndex;
+      break;
+    }
+
+    if (fieldType == kCollationKey) {
+      rv = GetCollationKey(tryHdr, m_sortType, EntryInfo2.key, colHandler);
+      NS_ASSERTION(NS_SUCCEEDED(rv), "failed to create collation key");
+      retStatus = FnSortIdKey(&EntryInfo1, &EntryInfo2, &comparisonContext);
+    } else if (fieldType == kU32) {
+      if (m_sortType == nsMsgViewSortType::byId) {
+        EntryInfo2.dword = EntryInfo2.id;
+      } else {
+        GetLongField(tryHdr, m_sortType, &EntryInfo2.dword, colHandler);
+      }
+
+      retStatus = FnSortIdUint32(&EntryInfo1, &EntryInfo2, &comparisonContext);
+    }
+
+    if (retStatus == 0) {
+      highIndex = tryIndex;
+      break;
+    }
+
+    if (retStatus < 0) {
+      highIndex = tryIndex;
+      // We already made sure tryIndex was at a thread at the top of the loop.
+    } else {
+      lowIndex = tryIndex + 1;
+      while (lowIndex < GetSize() && m_levels[lowIndex]) lowIndex++;
+    }
+  }
+
+  nsCOMPtr<nsIMsgDBHdr> resultHdr;
+  GetMsgHdrForViewIndex(highIndex, getter_AddRefs(resultHdr));
+
+  if (resultHdr != msgHdr) {
+    NS_WARNING("didn't find hdr");
+    highIndex = FindHdr(msgHdr);
+#ifdef DEBUG_David_Bienvenu
+    if (highIndex != nsMsgViewIndex_None) {
+      NS_WARNING("but find hdr did");
+      printf("level of found hdr = %d\n", m_levels[highIndex]);
+      ValidateSort();
+    }
+#endif
+    return highIndex;
+  }
+
+  return msgHdr == resultHdr ? highIndex : nsMsgViewIndex_None;
+}
+
+#ifdef DEBUG_David_Bienvenu
+
+void nsMsgDBView::InitEntryInfoForIndex(nsMsgViewIndex i, IdKey& EntryInfo) {
+  nsresult rv;
+  uint16_t maxLen;
+  eFieldType fieldType;
+
+  // Get the custom column handler for the primary sort and pass it first
+  // to GetFieldTypeAndLenForSort to get the fieldType and then either
+  // GetCollationKey or GetLongField.
+  nsIMsgCustomColumnHandler* colHandler = GetCurColumnHandler();
+
+  // The following may leave fieldType undefined.
+  rv = GetFieldTypeAndLenForSort(m_sortType, &maxLen, &fieldType, colHandler);
+  NS_ASSERTION(NS_SUCCEEDED(rv), "failed to obtain fieldType");
+
+  nsCOMPtr<nsIMsgDBHdr> msgHdr;
+  GetMsgHdrForViewIndex(i, getter_AddRefs(msgHdr));
+
+  msgHdr->GetMessageKey(&EntryInfo.id);
+  msgHdr->GetFolder(&EntryInfo.folder);
+  EntryInfo.folder->Release();
+
+  nsCOMPtr<nsIMsgDatabase> hdrDB;
+  EntryInfo.folder->GetMsgDatabase(getter_AddRefs(hdrDB));
+  switch (fieldType) {
+    case kCollationKey:
+      rv = GetCollationKey(msgHdr, m_sortType, EntryInfo.key, colHandler);
+      NS_ASSERTION(NS_SUCCEEDED(rv), "failed to create collation key");
+      break;
+    case kU32:
+      if (m_sortType == nsMsgViewSortType::byId)
+        EntryInfo.dword = EntryInfo.id;
+      else
+        GetLongField(msgHdr, m_sortType, &EntryInfo.dword, colHandler);
+
+      break;
+    default:
+      NS_ERROR("invalid field type");
+  }
+}
+
+void nsMsgDBView::ValidateSort() {
+  IdKey EntryInfo1, EntryInfo2;
+  nsCOMPtr<nsIMsgDBHdr> hdr1, hdr2;
+
+  uint16_t maxLen;
+  eFieldType fieldType;
+
+  // Get the custom column handler for the primary sort and pass it first
+  // to GetFieldTypeAndLenForSort to get the fieldType and then either
+  // GetCollationKey or GetLongField.
+  nsIMsgCustomColumnHandler* colHandler = GetCurColumnHandler();
+
+  // It is not entirely clear what we should do since,
+  // if fieldType is not available, there is no way to know
+  // how to compare the field to check for sorting.
+  // So we bomb out here. It is OK since this is debug code
+  // inside  #ifdef DEBUG_David_Bienvenu
+  nsresult rv =
+      GetFieldTypeAndLenForSort(m_sortType, &maxLen, &fieldType, colHandler);
+  NS_ASSERTION(NS_SUCCEEDED(rv), "failed to obtain fieldType");
+
+  viewSortInfo comparisonContext;
+  comparisonContext.view = this;
+  comparisonContext.isSecondarySort = false;
+  comparisonContext.ascendingSort =
+      (m_sortOrder == nsMsgViewSortOrder::ascending);
+  nsCOMPtr<nsIMsgDatabase> db;
+  GetDBForViewIndex(0, getter_AddRefs(db));
+  // This is only for comparing collation keys - it could be any db.
+  comparisonContext.db = db.get();
+
+  for (nsMsgViewIndex i = 0; i < m_keys.Length();) {
+    // Ignore non threads.
+    if (m_levels[i]) {
+      i++;
+      continue;
+    }
+
+    // Find next header.
+    nsMsgViewIndex j = i + 1;
+    while (j < m_keys.Length() && m_levels[j]) j++;
+
+    if (j == m_keys.Length()) break;
+
+    InitEntryInfoForIndex(i, EntryInfo1);
+    InitEntryInfoForIndex(j, EntryInfo2);
+    const void *pValue1 = &EntryInfo1, *pValue2 = &EntryInfo2;
+    int retStatus = 0;
+    if (fieldType == kCollationKey)
+      retStatus = FnSortIdKey(&pValue1, &pValue2, &comparisonContext);
+    else if (fieldType == kU32)
+      retStatus = FnSortIdUint32(&pValue1, &pValue2, &comparisonContext);
+
+    if (retStatus &&
+        (retStatus < 0) == (m_sortOrder == nsMsgViewSortOrder::ascending)) {
+      NS_ERROR("view not sorted correctly");
+      break;
+    }
+    // j is the new i.
+    i = j;
+  }
+}
+
+#endif
+
+nsresult nsMsgDBView::ListUnreadIdsInThread(
+    nsIMsgThread* threadHdr, nsMsgViewIndex startOfThreadViewIndex,
+    uint32_t* pNumListed) {
+  NS_ENSURE_ARG(threadHdr);
+  // These children ids should be in thread order.
+  nsMsgViewIndex viewIndex = startOfThreadViewIndex + 1;
+  *pNumListed = 0;
+  nsMsgKey topLevelMsgKey = m_keys[startOfThreadViewIndex];
+
+  uint32_t numChildren;
+  threadHdr->GetNumChildren(&numChildren);
+  uint32_t i;
+  for (i = 0; i < numChildren; i++) {
+    nsCOMPtr<nsIMsgDBHdr> msgHdr;
+    threadHdr->GetChildHdrAt(i, getter_AddRefs(msgHdr));
+    if (msgHdr != nullptr) {
+      if (!(m_viewFlags & nsMsgViewFlagsType::kShowIgnored)) {
+        bool killed;
+        msgHdr->GetIsKilled(&killed);
+        if (killed) continue;
+      }
+
+      nsMsgKey msgKey;
+      uint32_t msgFlags;
+      msgHdr->GetMessageKey(&msgKey);
+      msgHdr->GetFlags(&msgFlags);
+      bool isRead = AdjustReadFlag(msgHdr, &msgFlags);
+      if (!isRead) {
+        // Just make sure flag is right in db.
+        m_db->MarkHdrRead(msgHdr, false, nullptr);
+        if (msgKey != topLevelMsgKey) {
+          InsertMsgHdrAt(
+              viewIndex, msgHdr, msgKey, msgFlags,
+              FindLevelInThread(msgHdr, startOfThreadViewIndex, viewIndex));
+          viewIndex++;
+          (*pNumListed)++;
+        }
+      }
+    }
+  }
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsMsgDBView::OnHdrFlagsChanged(nsIMsgDBHdr* aHdrChanged, uint32_t aOldFlags,
+                               uint32_t aNewFlags,
+                               nsIDBChangeListener* aInstigator) {
+  // If we're not the instigator, update flags if this key is in our view.
+  if (aInstigator != this) {
+    NS_ENSURE_ARG_POINTER(aHdrChanged);
+    nsMsgKey msgKey;
+    aHdrChanged->GetMessageKey(&msgKey);
+    nsMsgViewIndex index = FindHdr(aHdrChanged);
+    if (index != nsMsgViewIndex_None) {
+      uint32_t viewOnlyFlags =
+          m_flags[index] & (MSG_VIEW_FLAGS | nsMsgMessageFlags::Elided);
+
+      // XXX what about saving the old view only flags, like IsThread and
+      // HasChildren?
+      // I think we'll want to save those away.
+      m_flags[index] = aNewFlags | viewOnlyFlags;
+      // Tell the view the extra flag changed, so it can
+      // update the previous view, if any.
+      OnExtraFlagChanged(index, aNewFlags);
+      NoteChange(index, 1, nsMsgViewNotificationCode::changed);
+    }
+
+    uint32_t deltaFlags = (aOldFlags ^ aNewFlags);
+    if (deltaFlags & (nsMsgMessageFlags::Read | nsMsgMessageFlags::New)) {
+      nsMsgViewIndex threadIndex =
+          ThreadIndexOfMsgHdr(aHdrChanged, index, nullptr, nullptr);
+
+      // May need to fix thread counts.
+      if (threadIndex != nsMsgViewIndex_None && threadIndex != index)
+        NoteChange(threadIndex, 1, nsMsgViewNotificationCode::changed);
+    }
+  }
+
+  // Don't need to propagate notifications, right?
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsMsgDBView::OnHdrDeleted(nsIMsgDBHdr* aHdrChanged, nsMsgKey aParentKey,
+                          int32_t aFlags, nsIDBChangeListener* aInstigator) {
+  nsMsgViewIndex deletedIndex = FindHdr(aHdrChanged);
+  if (IsValidIndex(deletedIndex)) {
+    // Check if this message is currently selected. If it is, tell the frontend
+    // to be prepared for a delete.
+    nsCOMPtr<nsIMsgDBViewCommandUpdater> commandUpdater(
+        do_QueryReferent(mCommandUpdater));
+    bool isMsgSelected = false;
+    if (mTreeSelection && commandUpdater) {
+      mTreeSelection->IsSelected(deletedIndex, &isMsgSelected);
+      if (isMsgSelected) commandUpdater->UpdateNextMessageAfterDelete();
+    }
+
+    RemoveByIndex(deletedIndex);
+
+    if (isMsgSelected) {
+      // Now tell the front end that the delete happened.
+      commandUpdater->SelectedMessageRemoved();
+    }
+  }
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsMsgDBView::OnHdrAdded(nsIMsgDBHdr* aHdrChanged, nsMsgKey aParentKey,
+                        int32_t aFlags, nsIDBChangeListener* aInstigator) {
+  return OnNewHeader(aHdrChanged, aParentKey, false);
+  // Probably also want to pass that parent key in, since we went to the
+  // trouble of figuring out what it is.
+}
+
+NS_IMETHODIMP
+nsMsgDBView::OnHdrPropertyChanged(nsIMsgDBHdr* aHdrToChange,
+                                  const nsACString& property, bool aPreChange,
+                                  uint32_t* aStatus,
+                                  nsIDBChangeListener* aInstigator) {
+  if (aPreChange) return NS_OK;
+
+  if (aHdrToChange) {
+    nsMsgViewIndex index = FindHdr(aHdrToChange);
+    if (index != nsMsgViewIndex_None)
+      NoteChange(index, 1, nsMsgViewNotificationCode::changed);
+  }
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsMsgDBView::OnParentChanged(nsMsgKey aKeyChanged, nsMsgKey oldParent,
+                             nsMsgKey newParent,
+                             nsIDBChangeListener* aInstigator) {
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsMsgDBView::OnAnnouncerGoingAway(nsIDBChangeAnnouncer* instigator) {
+  if (m_db) {
+    m_db->RemoveListener(this);
+    m_db = nullptr;
+  }
+
+  int32_t saveSize = GetSize();
+  ClearHdrCache();
+
+  // This is important, because the tree will ask us for our
+  // row count, which get determine from the number of keys.
+  m_keys.Clear();
+  // Be consistent.
+  m_flags.Clear();
+  m_levels.Clear();
+
+  // Tell the tree all the rows have gone away.
+  if (mTree) mTree->RowCountChanged(0, -saveSize);
+  if (mJSTree) mJSTree->RowCountChanged(0, -saveSize);
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsMsgDBView::OnEvent(nsIMsgDatabase* aDB, const char* aEvent) {
+  if (!strcmp(aEvent, "DBOpened")) m_db = aDB;
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsMsgDBView::OnReadChanged(nsIDBChangeListener* aInstigator) { return NS_OK; }
+
+NS_IMETHODIMP
+nsMsgDBView::OnJunkScoreChanged(nsIDBChangeListener* aInstigator) {
+  return NS_OK;
+}
+
+void nsMsgDBView::ClearHdrCache() {
+  m_cachedHdr = nullptr;
+  m_cachedMsgKey = nsMsgKey_None;
+}
+
+NS_IMETHODIMP
+nsMsgDBView::SetSuppressChangeNotifications(bool aSuppressChangeNotifications) {
+  mSuppressChangeNotification = aSuppressChangeNotifications;
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsMsgDBView::GetSuppressChangeNotifications(
+    bool* aSuppressChangeNotifications) {
+  NS_ENSURE_ARG_POINTER(aSuppressChangeNotifications);
+  *aSuppressChangeNotifications = mSuppressChangeNotification;
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsMsgDBView::NoteChange(nsMsgViewIndex firstLineChanged, int32_t numChanged,
+                        nsMsgViewNotificationCodeValue changeType) {
+  if ((mTree || mJSTree) && !mSuppressChangeNotification) {
+    switch (changeType) {
+      case nsMsgViewNotificationCode::changed:
+        if (mTree)
+          mTree->InvalidateRange(firstLineChanged,
+                                 firstLineChanged + numChanged - 1);
+        if (mJSTree)
+          mJSTree->InvalidateRange(firstLineChanged,
+                                   firstLineChanged + numChanged - 1);
+        break;
+      case nsMsgViewNotificationCode::insertOrDelete:
+        if (numChanged < 0) mRemovingRow = true;
+
+        // The caller needs to have adjusted m_keys before getting here, since
+        // RowCountChanged() will call our GetRowCount().
+        if (mTree) mTree->RowCountChanged(firstLineChanged, numChanged);
+        if (mJSTree) mJSTree->RowCountChanged(firstLineChanged, numChanged);
+        mRemovingRow = false;
+        [[fallthrough]];
+      case nsMsgViewNotificationCode::all:
+        ClearHdrCache();
+        break;
+    }
+  }
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsMsgDBView::GetSortOrder(nsMsgViewSortOrderValue* aSortOrder) {
+  NS_ENSURE_ARG_POINTER(aSortOrder);
+  *aSortOrder = m_sortOrder;
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsMsgDBView::GetSortType(nsMsgViewSortTypeValue* aSortType) {
+  NS_ENSURE_ARG_POINTER(aSortType);
+  *aSortType = m_sortType;
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsMsgDBView::SetSortType(nsMsgViewSortTypeValue aSortType) {
+  m_sortType = aSortType;
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsMsgDBView::GetViewType(nsMsgViewTypeValue* aViewType) {
+  NS_ERROR("you should be overriding this");
+  return NS_ERROR_UNEXPECTED;
+}
+
+NS_IMETHODIMP
+nsMsgDBView::GetSecondarySortOrder(nsMsgViewSortOrderValue* aSortOrder) {
+  NS_ENSURE_ARG_POINTER(aSortOrder);
+  *aSortOrder = m_secondarySortOrder;
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsMsgDBView::SetSecondarySortOrder(nsMsgViewSortOrderValue aSortOrder) {
+  m_secondarySortOrder = aSortOrder;
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsMsgDBView::GetSecondarySortType(nsMsgViewSortTypeValue* aSortType) {
+  NS_ENSURE_ARG_POINTER(aSortType);
+  *aSortType = m_secondarySort;
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsMsgDBView::SetSecondarySortType(nsMsgViewSortTypeValue aSortType) {
+  m_secondarySort = aSortType;
+  return NS_OK;
+}
+
+nsresult nsMsgDBView::PersistFolderInfo(nsIDBFolderInfo** dbFolderInfo) {
+  nsresult rv = m_db->GetDBFolderInfo(dbFolderInfo);
+  NS_ENSURE_SUCCESS(rv, rv);
+  // Save off sort type and order, view type and flags.
+  (*dbFolderInfo)->SetSortType(m_sortType);
+  (*dbFolderInfo)->SetSortOrder(m_sortOrder);
+  (*dbFolderInfo)->SetViewFlags(m_viewFlags);
+  nsMsgViewTypeValue viewType;
+  GetViewType(&viewType);
+  (*dbFolderInfo)->SetViewType(viewType);
+  return rv;
+}
+
+NS_IMETHODIMP
+nsMsgDBView::GetViewFlags(nsMsgViewFlagsTypeValue* aViewFlags) {
+  NS_ENSURE_ARG_POINTER(aViewFlags);
+  *aViewFlags = m_viewFlags;
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsMsgDBView::SetViewFlags(nsMsgViewFlagsTypeValue aViewFlags) {
+  // If we're turning off threaded display, we need to expand all so that all
+  // messages will be displayed.
+  if (m_viewFlags & nsMsgViewFlagsType::kThreadedDisplay &&
+      !(aViewFlags & nsMsgViewFlagsType::kThreadedDisplay)) {
+    ExpandAll();
+    // Invalidate the sort so sorting will do something.
+    m_sortValid = false;
+  }
+
+  m_viewFlags = aViewFlags;
+
+  if (m_viewFolder) {
+    nsCOMPtr<nsIMsgDatabase> db;
+    nsCOMPtr<nsIDBFolderInfo> folderInfo;
+    nsresult rv = m_viewFolder->GetDBFolderInfoAndDB(getter_AddRefs(folderInfo),
+                                                     getter_AddRefs(db));
+    NS_ENSURE_SUCCESS(rv, rv);
+    return folderInfo->SetViewFlags(aViewFlags);
+  } else
+    return NS_OK;
+}
+
+nsresult nsMsgDBView::MarkThreadOfMsgRead(nsMsgKey msgId,
+                                          nsMsgViewIndex msgIndex,
+                                          nsTArray<nsMsgKey>& idsMarkedRead,
+                                          bool bRead) {
+  nsCOMPtr<nsIMsgThread> threadHdr;
+  nsresult rv = GetThreadContainingIndex(msgIndex, getter_AddRefs(threadHdr));
+  NS_ENSURE_SUCCESS(rv, rv);
+
+  nsMsgViewIndex threadIndex;
+
+  NS_ASSERTION(threadHdr, "threadHdr is null");
+  if (!threadHdr) return NS_MSG_MESSAGE_NOT_FOUND;
+
+  nsCOMPtr<nsIMsgDBHdr> firstHdr;
+  rv = threadHdr->GetChildHdrAt(0, getter_AddRefs(firstHdr));
+  NS_ENSURE_SUCCESS(rv, rv);
+  nsMsgKey firstHdrId;
+  firstHdr->GetMessageKey(&firstHdrId);
+  if (msgId != firstHdrId)
+    threadIndex = GetIndexOfFirstDisplayedKeyInThread(threadHdr);
+  else
+    threadIndex = msgIndex;
+
+  return MarkThreadRead(threadHdr, threadIndex, idsMarkedRead, bRead);
+}
+
+nsresult nsMsgDBView::MarkThreadRead(nsIMsgThread* threadHdr,
+                                     nsMsgViewIndex threadIndex,
+                                     nsTArray<nsMsgKey>& idsMarkedRead,
+                                     bool bRead) {
+  uint32_t numChildren;
+  threadHdr->GetNumChildren(&numChildren);
+  idsMarkedRead.SetCapacity(numChildren);
+  for (int32_t childIndex = 0; childIndex < (int32_t)numChildren;
+       childIndex++) {
+    nsCOMPtr<nsIMsgDBHdr> msgHdr;
+    threadHdr->GetChildHdrAt(childIndex, getter_AddRefs(msgHdr));
+    NS_ASSERTION(msgHdr, "msgHdr is null");
+    if (!msgHdr) continue;
+
+    bool isRead;
+    nsMsgKey hdrMsgId;
+    msgHdr->GetMessageKey(&hdrMsgId);
+    nsCOMPtr<nsIMsgDatabase> db;
+    nsresult rv = GetDBForHeader(msgHdr, getter_AddRefs(db));
+    NS_ENSURE_SUCCESS(rv, rv);
+    db->IsRead(hdrMsgId, &isRead);
+
+    if (isRead != bRead) {
+      // MarkHdrRead will change the unread count on the thread.
+      db->MarkHdrRead(msgHdr, bRead, nullptr);
+      // Insert at the front. Should we insert at the end?
+      idsMarkedRead.InsertElementAt(0, hdrMsgId);
+    }
+  }
+
+  return NS_OK;
+}
+
+bool nsMsgDBView::AdjustReadFlag(nsIMsgDBHdr* msgHdr, uint32_t* msgFlags) {
+  // If we're a cross-folder view, just bail on this.
+  if (GetFolders()) return *msgFlags & nsMsgMessageFlags::Read;
+
+  bool isRead = false;
+  nsMsgKey msgKey;
+  msgHdr->GetMessageKey(&msgKey);
+  m_db->IsRead(msgKey, &isRead);
+  // Just make sure flag is right in db.
+#ifdef DEBUG_David_Bienvenu
+  NS_ASSERTION(isRead == ((*msgFlags & nsMsgMessageFlags::Read) != 0),
+               "msgFlags out of sync");
+#endif
+  if (isRead)
+    *msgFlags |= nsMsgMessageFlags::Read;
+  else
+    *msgFlags &= ~nsMsgMessageFlags::Read;
+
+  m_db->MarkHdrRead(msgHdr, isRead, nullptr);
+  return isRead;
+}
+
+// Starting from startIndex, performs the passed in navigation, including
+// any marking read needed, and returns the resultId and resultIndex of the
+// destination of the navigation.  If no message is found in the view,
+// it returns a resultId of nsMsgKey_None and an resultIndex of
+// nsMsgViewIndex_None.
+NS_IMETHODIMP
+nsMsgDBView::ViewNavigate(nsMsgNavigationTypeValue motion, nsMsgKey* pResultKey,
+                          nsMsgViewIndex* pResultIndex,
+                          nsMsgViewIndex* pThreadIndex, bool wrap) {
+  NS_ENSURE_ARG_POINTER(pResultKey);
+  NS_ENSURE_ARG_POINTER(pResultIndex);
+  NS_ENSURE_ARG_POINTER(pThreadIndex);
+
+  int32_t currentIndex;
+  nsMsgViewIndex startIndex;
+
+  if (!mTreeSelection) {
+    // We must be in stand alone message mode.
+    currentIndex = FindViewIndex(m_currentlyDisplayedMsgKey);
+  } else {
+    nsresult rv = mTreeSelection->GetCurrentIndex(&currentIndex);
+    NS_ENSURE_SUCCESS(rv, rv);
+  }
+
+  startIndex = currentIndex;
+  return nsMsgDBView::NavigateFromPos(motion, startIndex, pResultKey,
+                                      pResultIndex, pThreadIndex, wrap);
+}
+
+nsresult nsMsgDBView::NavigateFromPos(nsMsgNavigationTypeValue motion,
+                                      nsMsgViewIndex startIndex,
+                                      nsMsgKey* pResultKey,
+                                      nsMsgViewIndex* pResultIndex,
+                                      nsMsgViewIndex* pThreadIndex, bool wrap) {
+  nsresult rv = NS_OK;
+  nsMsgKey resultThreadKey;
+  nsMsgViewIndex curIndex;
+  nsMsgViewIndex lastIndex =
+      (GetSize() > 0) ? (nsMsgViewIndex)GetSize() - 1 : nsMsgViewIndex_None;
+  nsMsgViewIndex threadIndex = nsMsgViewIndex_None;
+
+  // If there aren't any messages in the view, bail out.
+  if (GetSize() <= 0) {
+    *pResultIndex = nsMsgViewIndex_None;
+    *pResultKey = nsMsgKey_None;
+    return NS_OK;
+  }
+  *pResultKey = nsMsgKey_None;
+
+  switch (motion) {
+    case nsMsgNavigationType::firstMessage:
+      *pResultIndex = 0;
+      *pResultKey = m_keys[0];
+      break;
+    case nsMsgNavigationType::nextMessage:
+      // Return same index and id on next on last message.
+      *pResultIndex = std::min(startIndex + 1, lastIndex);
+      *pResultKey = m_keys[*pResultIndex];
+      break;
+    case nsMsgNavigationType::previousMessage:
+      if (startIndex != nsMsgViewIndex_None && startIndex > 0) {
+        *pResultIndex = startIndex - 1;
+      }
+      if (IsValidIndex(*pResultIndex)) *pResultKey = m_keys[*pResultIndex];
+      break;
+    case nsMsgNavigationType::lastMessage:
+      *pResultIndex = lastIndex;
+      *pResultKey = m_keys[*pResultIndex];
+      break;
+    case nsMsgNavigationType::firstFlagged:
+      rv = FindFirstFlagged(pResultIndex);
+      if (IsValidIndex(*pResultIndex)) *pResultKey = m_keys[*pResultIndex];
+      break;
+    case nsMsgNavigationType::nextFlagged:
+      rv = FindNextFlagged(startIndex + 1, pResultIndex);
+      if (IsValidIndex(*pResultIndex)) *pResultKey = m_keys[*pResultIndex];
+      break;
+    case nsMsgNavigationType::previousFlagged:
+      rv = FindPrevFlagged(startIndex, pResultIndex);
+      if (IsValidIndex(*pResultIndex)) *pResultKey = m_keys[*pResultIndex];
+      break;
+    case nsMsgNavigationType::firstNew:
+      rv = FindFirstNew(pResultIndex);
+      if (IsValidIndex(*pResultIndex)) *pResultKey = m_keys[*pResultIndex];
+      break;
+    case nsMsgNavigationType::firstUnreadMessage:
+      startIndex = nsMsgViewIndex_None;
+      // Note fall through - is this motion ever used?
+      [[fallthrough]];
+    case nsMsgNavigationType::nextUnreadMessage:
+      for (curIndex = (startIndex == nsMsgViewIndex_None) ? 0 : startIndex;
+           curIndex <= lastIndex && lastIndex != nsMsgViewIndex_None;
+           curIndex++) {
+        uint32_t flags = m_flags[curIndex];
+        // Don't return start index since navigate should move.
+        if (!(flags & (nsMsgMessageFlags::Read | MSG_VIEW_FLAG_DUMMY)) &&
+            (curIndex != startIndex)) {
+          *pResultIndex = curIndex;
+          *pResultKey = m_keys[*pResultIndex];
+          break;
+        }
+
+        // Check for collapsed thread with new children.
+        if ((m_viewFlags & nsMsgViewFlagsType::kThreadedDisplay) &&
+            flags & MSG_VIEW_FLAG_ISTHREAD &&
+            flags & nsMsgMessageFlags::Elided) {
+          nsCOMPtr<nsIMsgThread> threadHdr;
+          GetThreadContainingIndex(curIndex, getter_AddRefs(threadHdr));
+          NS_ENSURE_SUCCESS(rv, rv);
+
+          NS_ASSERTION(threadHdr, "threadHdr is null");
+          if (!threadHdr) continue;
+
+          uint32_t numUnreadChildren;
+          threadHdr->GetNumUnreadChildren(&numUnreadChildren);
+          if (numUnreadChildren > 0) {
+            uint32_t numExpanded;
+            ExpandByIndex(curIndex, &numExpanded);
+            lastIndex += numExpanded;
+            if (pThreadIndex) *pThreadIndex = curIndex;
+          }
+        }
+      }
+
+      if (curIndex > lastIndex) {
+        // Wrap around by starting at index 0.
+        if (wrap) {
+          nsMsgKey startKey = GetAt(startIndex);
+          rv = NavigateFromPos(nsMsgNavigationType::nextUnreadMessage,
+                               nsMsgViewIndex_None, pResultKey, pResultIndex,
+                               pThreadIndex, false);
+
+          if (*pResultKey == startKey) {
+            // wrapped around and found start message!
+            *pResultIndex = nsMsgViewIndex_None;
+            *pResultKey = nsMsgKey_None;
+          }
+        } else {
+          *pResultIndex = nsMsgViewIndex_None;
+          *pResultKey = nsMsgKey_None;
+        }
+      }
+      break;
+    case nsMsgNavigationType::previousUnreadMessage:
+      if (!IsValidIndex(startIndex)) break;
+
+      rv = FindPrevUnread(m_keys[startIndex], pResultKey, &resultThreadKey);
+      if (NS_SUCCEEDED(rv)) {
+        *pResultIndex = FindViewIndex(*pResultKey);
+        if (*pResultKey != resultThreadKey &&
+            (m_viewFlags & nsMsgViewFlagsType::kThreadedDisplay)) {
+          threadIndex = GetThreadIndex(*pResultIndex);
+          if (*pResultIndex == nsMsgViewIndex_None) {
+            nsCOMPtr<nsIMsgThread> threadHdr;
+            nsCOMPtr<nsIMsgDBHdr> msgHdr;
+            rv = m_db->GetMsgHdrForKey(*pResultKey, getter_AddRefs(msgHdr));
+            NS_ENSURE_SUCCESS(rv, rv);
+            rv = GetThreadContainingMsgHdr(msgHdr, getter_AddRefs(threadHdr));
+            NS_ENSURE_SUCCESS(rv, rv);
+
+            NS_ASSERTION(threadHdr, "threadHdr is null");
+            if (threadHdr) break;
+
+            uint32_t numUnreadChildren;
+            threadHdr->GetNumUnreadChildren(&numUnreadChildren);
+            if (numUnreadChildren > 0) {
+              uint32_t numExpanded;
+              ExpandByIndex(threadIndex, &numExpanded);
+            }
+
+            *pResultIndex = FindViewIndex(*pResultKey);
+          }
+        }
+
+        if (pThreadIndex) *pThreadIndex = threadIndex;
+      }
+      break;
+    case nsMsgNavigationType::lastUnreadMessage:
+      break;
+    case nsMsgNavigationType::nextUnreadThread:
+      if (startIndex != nsMsgViewIndex_None) {
+        ApplyCommandToIndices(nsMsgViewCommandType::markThreadRead,
+                              {startIndex});
+      }
+
+      return NavigateFromPos(nsMsgNavigationType::nextUnreadMessage, startIndex,
+                             pResultKey, pResultIndex, pThreadIndex, true);
+    case nsMsgNavigationType::toggleThreadKilled: {
+      bool resultKilled;
+      nsMsgViewIndexArray selection;
+      GetIndicesForSelection(selection);
+      ToggleIgnored(selection, &threadIndex, &resultKilled);
+      if (resultKilled) {
+        return NavigateFromPos(nsMsgNavigationType::nextUnreadThread,
+                               threadIndex, pResultKey, pResultIndex,
+                               pThreadIndex, true);
+      } else {
+        *pResultIndex = nsMsgViewIndex_None;
+        *pResultKey = nsMsgKey_None;
+        return NS_OK;
+      }
+    }
+    case nsMsgNavigationType::toggleSubthreadKilled: {
+      bool resultKilled;
+      nsMsgViewIndexArray selection;
+      GetIndicesForSelection(selection);
+      ToggleMessageKilled(selection, &threadIndex, &resultKilled);
+      if (resultKilled) {
+        return NavigateFromPos(nsMsgNavigationType::nextUnreadMessage,
+                               threadIndex, pResultKey, pResultIndex,
+                               pThreadIndex, true);
+      } else {
+        *pResultIndex = nsMsgViewIndex_None;
+        *pResultKey = nsMsgKey_None;
+        return NS_OK;
+      }
+    }
+    // Check where navigate says this will take us. If we have the message
+    // in the view, return it. Otherwise, return an error.
+    case nsMsgNavigationType::back:
+    case nsMsgNavigationType::forward:
+      // Handled purely in JS.
+      *pResultIndex = nsMsgViewIndex_None;
+      *pResultKey = nsMsgKey_None;
+      break;
+    default:
+      NS_ERROR("unsupported motion");
+      break;
+  }
+
+  return NS_OK;
+}
+
+// Note that these routines do NOT expand collapsed threads! This mimics the
+// old behaviour, but it's also because we don't remember whether a thread
+// contains a flagged message the same way we remember if a thread contains
+// new messages. It would be painful to dive down into each collapsed thread
+// to update navigate status. We could cache this info, but it would still be
+// expensive the first time this status needs to get updated.
+nsresult nsMsgDBView::FindNextFlagged(nsMsgViewIndex startIndex,
+                                      nsMsgViewIndex* pResultIndex) {
+  nsMsgViewIndex lastIndex = (nsMsgViewIndex)GetSize() - 1;
+  nsMsgViewIndex curIndex;
+
+  *pResultIndex = nsMsgViewIndex_None;
+
+  if (GetSize() > 0) {
+    for (curIndex = startIndex; curIndex <= lastIndex; curIndex++) {
+      uint32_t flags = m_flags[curIndex];
+      if (flags & nsMsgMessageFlags::Marked) {
+        *pResultIndex = curIndex;
+        break;
+      }
+    }
+  }
+
+  return NS_OK;
+}
+
+nsresult nsMsgDBView::FindFirstNew(nsMsgViewIndex* pResultIndex) {
+  if (m_db) {
+    nsMsgKey firstNewKey = nsMsgKey_None;
+    m_db->GetFirstNew(&firstNewKey);
+    *pResultIndex = (firstNewKey != nsMsgKey_None) ? FindKey(firstNewKey, true)
+                                                   : nsMsgViewIndex_None;
+  }
+
+  return NS_OK;
+}
+
+nsresult nsMsgDBView::FindPrevUnread(nsMsgKey startKey, nsMsgKey* pResultKey,
+                                     nsMsgKey* resultThreadId) {
+  nsMsgViewIndex startIndex = FindViewIndex(startKey);
+  nsMsgViewIndex curIndex = startIndex;
+  nsresult rv = NS_MSG_MESSAGE_NOT_FOUND;
+
+  if (startIndex == nsMsgViewIndex_None) return NS_MSG_MESSAGE_NOT_FOUND;
+
+  *pResultKey = nsMsgKey_None;
+  if (resultThreadId) *resultThreadId = nsMsgKey_None;
+
+  for (; (int)curIndex >= 0 && (*pResultKey == nsMsgKey_None); curIndex--) {
+    uint32_t flags = m_flags[curIndex];
+    if (curIndex != startIndex && flags & MSG_VIEW_FLAG_ISTHREAD &&
+        flags & nsMsgMessageFlags::Elided) {
+      NS_ERROR("fix this");
+      // nsMsgKey threadId = m_keys[curIndex];
+      // rv = m_db->GetUnreadKeyInThread(threadId, pResultKey, resultThreadId);
+      if (NS_SUCCEEDED(rv) && (*pResultKey != nsMsgKey_None)) break;
+    }
+
+    if (!(flags & (nsMsgMessageFlags::Read | MSG_VIEW_FLAG_DUMMY)) &&
+        (curIndex != startIndex)) {
+      *pResultKey = m_keys[curIndex];
+      rv = NS_OK;
+      break;
+    }
+  }
+
+  // Found unread message but we don't know the thread.
+  NS_ASSERTION(!(*pResultKey != nsMsgKey_None && resultThreadId &&
+                 *resultThreadId == nsMsgKey_None),
+               "fix this");
+  return rv;
+}
+
+nsresult nsMsgDBView::FindFirstFlagged(nsMsgViewIndex* pResultIndex) {
+  return FindNextFlagged(0, pResultIndex);
+}
+
+nsresult nsMsgDBView::FindPrevFlagged(nsMsgViewIndex startIndex,
+                                      nsMsgViewIndex* pResultIndex) {
+  nsMsgViewIndex curIndex;
+
+  *pResultIndex = nsMsgViewIndex_None;
+
+  if (GetSize() > 0 && IsValidIndex(startIndex)) {
+    curIndex = startIndex;
+    do {
+      if (curIndex != 0) curIndex--;
+
+      uint32_t flags = m_flags[curIndex];
+      if (flags & nsMsgMessageFlags::Marked) {
+        *pResultIndex = curIndex;
+        break;
+      }
+    } while (curIndex != 0);
+  }
+
+  return NS_OK;
+}
+
+bool nsMsgDBView::IsValidIndex(nsMsgViewIndex index) {
+  return index != nsMsgViewIndex_None &&
+         (index < (nsMsgViewIndex)m_keys.Length());
+}
+
+nsresult nsMsgDBView::OrExtraFlag(nsMsgViewIndex index, uint32_t orflag) {
+  uint32_t flag;
+  if (!IsValidIndex(index)) return NS_MSG_INVALID_DBVIEW_INDEX;
+
+  flag = m_flags[index];
+  flag |= orflag;
+  m_flags[index] = flag;
+  OnExtraFlagChanged(index, flag);
+  return NS_OK;
+}
+
+nsresult nsMsgDBView::AndExtraFlag(nsMsgViewIndex index, uint32_t andflag) {
+  uint32_t flag;
+  if (!IsValidIndex(index)) return NS_MSG_INVALID_DBVIEW_INDEX;
+
+  flag = m_flags[index];
+  flag &= andflag;
+  m_flags[index] = flag;
+  OnExtraFlagChanged(index, flag);
+  return NS_OK;
+}
+
+nsresult nsMsgDBView::SetExtraFlag(nsMsgViewIndex index, uint32_t extraflag) {
+  if (!IsValidIndex(index)) return NS_MSG_INVALID_DBVIEW_INDEX;
+
+  m_flags[index] = extraflag;
+  OnExtraFlagChanged(index, extraflag);
+  return NS_OK;
+}
+
+nsresult nsMsgDBView::ToggleIgnored(nsTArray<nsMsgViewIndex> const& selection,
+                                    nsMsgViewIndex* resultIndex,
+                                    bool* resultToggleState) {
+  nsCOMPtr<nsIMsgThread> thread;
+
+  // Ignored state is toggled based on the first selected thread.
+  nsMsgViewIndex threadIndex =
+      GetThreadFromMsgIndex(selection[0], getter_AddRefs(thread));
+  NS_ENSURE_STATE(thread);
+  uint32_t threadFlags;
+  thread->GetFlags(&threadFlags);
+  uint32_t ignored = threadFlags & nsMsgMessageFlags::Ignored;
+
+  // Process threads in reverse order.
+  // Otherwise collapsing the threads will invalidate the indices.
+  threadIndex = nsMsgViewIndex_None;
+  uint32_t numIndices = selection.Length();
+  while (numIndices) {
+    numIndices--;
+    if (selection[numIndices] < threadIndex) {
+      threadIndex =
+          GetThreadFromMsgIndex(selection[numIndices], getter_AddRefs(thread));
+      thread->GetFlags(&threadFlags);
+      if ((threadFlags & nsMsgMessageFlags::Ignored) == ignored)
+        SetThreadIgnored(thread, threadIndex, !ignored);
+    }
+  }
+
+  if (resultIndex) *resultIndex = threadIndex;
+
+  if (resultToggleState) *resultToggleState = !ignored;
+
+  return NS_OK;
+}
+
+nsresult nsMsgDBView::ToggleMessageKilled(
+    nsTArray<nsMsgViewIndex> const& selection, nsMsgViewIndex* resultIndex,
+    bool* resultToggleState) {
+  NS_ENSURE_ARG_POINTER(resultToggleState);
+
+  nsCOMPtr<nsIMsgDBHdr> header;
+  // Ignored state is toggled based on the first selected message.
+  nsresult rv = GetMsgHdrForViewIndex(selection[0], getter_AddRefs(header));
+  NS_ENSURE_SUCCESS(rv, rv);
+
+  uint32_t msgFlags;
+  header->GetFlags(&msgFlags);
+  uint32_t ignored = msgFlags & nsMsgMessageFlags::Ignored;
+
+  // Process messages in reverse order.
+  // Otherwise the indices may be invalidated.
+  nsMsgViewIndex msgIndex = nsMsgViewIndex_None;
+  uint32_t numIndices = selection.Length();
+  while (numIndices) {
+    numIndices--;
+    if (selection[numIndices] < msgIndex) {
+      msgIndex = selection[numIndices];
+      rv = GetMsgHdrForViewIndex(msgIndex, getter_AddRefs(header));
+      NS_ENSURE_SUCCESS(rv, rv);
+      header->GetFlags(&msgFlags);
+      if ((msgFlags & nsMsgMessageFlags::Ignored) == ignored)
+        SetSubthreadKilled(header, msgIndex, !ignored);
+    }
+  }
+
+  if (resultIndex) *resultIndex = msgIndex;
+
+  if (resultToggleState) *resultToggleState = !ignored;
+
+  return NS_OK;
+}
+
+nsMsgViewIndex nsMsgDBView::GetThreadFromMsgIndex(nsMsgViewIndex index,
+                                                  nsIMsgThread** threadHdr) {
+  if (threadHdr == nullptr) return nsMsgViewIndex_None;
+  nsMsgKey msgKey = GetAt(index);
+
+  nsresult rv = GetThreadContainingIndex(index, threadHdr);
+  NS_ENSURE_SUCCESS(rv, nsMsgViewIndex_None);
+
+  if (*threadHdr == nullptr) return nsMsgViewIndex_None;
+
+  nsMsgKey threadKey;
+  (*threadHdr)->GetThreadKey(&threadKey);
+  nsMsgViewIndex threadIndex;
+  if (msgKey != threadKey)
+    threadIndex = GetIndexOfFirstDisplayedKeyInThread(*threadHdr);
+  else
+    threadIndex = index;
+  return threadIndex;
+}
+
+nsresult nsMsgDBView::ToggleWatched(nsTArray<nsMsgViewIndex> const& selection) {
+  MOZ_ASSERT(!selection.IsEmpty());
+  nsCOMPtr<nsIMsgThread> thread;
+
+  // Watched state is toggled based on the first selected thread.
+  nsMsgViewIndex threadIndex =
+      GetThreadFromMsgIndex(selection[0], getter_AddRefs(thread));
+  NS_ENSURE_STATE(thread);
+  uint32_t threadFlags;
+  thread->GetFlags(&threadFlags);
+  uint32_t watched = threadFlags & nsMsgMessageFlags::Watched;
+
+  // Process threads in reverse order for consistency with ToggleIgnored.
+  threadIndex = nsMsgViewIndex_None;
+  uint32_t numIndices = selection.Length();
+  while (numIndices) {
+    numIndices--;
+    if (selection[numIndices] < threadIndex) {
+      threadIndex =
+          GetThreadFromMsgIndex(selection[numIndices], getter_AddRefs(thread));
+      thread->GetFlags(&threadFlags);
+      if ((threadFlags & nsMsgMessageFlags::Watched) == watched)
+        SetThreadWatched(thread, threadIndex, !watched);
+    }
+  }
+
+  return NS_OK;
+}
+
+nsresult nsMsgDBView::SetThreadIgnored(nsIMsgThread* thread,
+                                       nsMsgViewIndex threadIndex,
+                                       bool ignored) {
+  if (!IsValidIndex(threadIndex)) return NS_MSG_INVALID_DBVIEW_INDEX;
+
+  NoteChange(threadIndex, 1, nsMsgViewNotificationCode::changed);
+  if (ignored) {
+    nsTArray<nsMsgKey> idsMarkedRead;
+    MarkThreadRead(thread, threadIndex, idsMarkedRead, true);
+    CollapseByIndex(threadIndex, nullptr);
+  }
+
+  if (!m_db) return NS_ERROR_FAILURE;
+
+  return m_db->MarkThreadIgnored(thread, m_keys[threadIndex], ignored, this);
+}
+
+nsresult nsMsgDBView::SetSubthreadKilled(nsIMsgDBHdr* header,
+                                         nsMsgViewIndex msgIndex,
+                                         bool ignored) {
+  if (!IsValidIndex(msgIndex)) return NS_MSG_INVALID_DBVIEW_INDEX;
+
+  NoteChange(msgIndex, 1, nsMsgViewNotificationCode::changed);
+
+  if (!m_db) return NS_ERROR_FAILURE;
+
+  nsresult rv = m_db->MarkHeaderKilled(header, ignored, this);
+  NS_ENSURE_SUCCESS(rv, rv);
+
+  if (ignored) {
+    nsCOMPtr<nsIMsgThread> thread;
+    nsresult rv;
+    rv = GetThreadContainingMsgHdr(header, getter_AddRefs(thread));
+    // So we didn't mark threads read.
+    if (NS_FAILED(rv)) return NS_OK;
+
+    uint32_t children, current;
+    thread->GetNumChildren(&children);
+
+    nsMsgKey headKey;
+    header->GetMessageKey(&headKey);
+
+    for (current = 0; current < children; current++) {
+      nsMsgKey newKey;
+      thread->GetChildKeyAt(current, &newKey);
+      if (newKey == headKey) break;
+    }
+
+    // Process all messages, starting with this message.
+    for (; current < children; current++) {
+      nsCOMPtr<nsIMsgDBHdr> nextHdr;
+      bool isKilled;
+
+      thread->GetChildHdrAt(current, getter_AddRefs(nextHdr));
+      nextHdr->GetIsKilled(&isKilled);
+
+      // Ideally, the messages should stop processing here.
+      // However, the children are ordered not by thread...
+      if (isKilled) nextHdr->MarkRead(true);
+    }
+  }
+
+  return NS_OK;
+}
+
+nsresult nsMsgDBView::SetThreadWatched(nsIMsgThread* thread,
+                                       nsMsgViewIndex index, bool watched) {
+  if (!IsValidIndex(index)) return NS_MSG_INVALID_DBVIEW_INDEX;
+
+  nsresult rv = m_db->MarkThreadWatched(thread, m_keys[index], watched, this);
+  NoteChange(index, 1, nsMsgViewNotificationCode::changed);
+  return rv;
+}
+
+NS_IMETHODIMP
+nsMsgDBView::GetMsgFolder(nsIMsgFolder** aMsgFolder) {
+  NS_ENSURE_ARG_POINTER(aMsgFolder);
+  NS_IF_ADDREF(*aMsgFolder = m_folder);
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsMsgDBView::SetViewFolder(nsIMsgFolder* aMsgFolder) {
+  m_viewFolder = aMsgFolder;
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsMsgDBView::GetViewFolder(nsIMsgFolder** aMsgFolder) {
+  NS_ENSURE_ARG_POINTER(aMsgFolder);
+  NS_IF_ADDREF(*aMsgFolder = m_viewFolder);
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsMsgDBView::GetNumSelected(uint32_t* aNumSelected) {
+  NS_ENSURE_ARG_POINTER(aNumSelected);
+
+  if (!mTreeSelection) {
+    // No tree selection can mean we're in the stand alone mode.
+    *aNumSelected = (m_currentlyDisplayedMsgKey != nsMsgKey_None) ? 1 : 0;
+    return NS_OK;
+  }
+
+  bool includeCollapsedMsgs = OperateOnMsgsInCollapsedThreads();
+
+  // We call this a lot from the front end JS, so make it fast.
+  nsresult rv = mTreeSelection->GetCount((int32_t*)aNumSelected);
+  if (!*aNumSelected || !includeCollapsedMsgs ||
+      !(m_viewFlags & nsMsgViewFlagsType::kThreadedDisplay))
+    return rv;
+
+  int32_t numSelectedIncludingCollapsed = *aNumSelected;
+  nsMsgViewIndexArray selection;
+  GetIndicesForSelection(selection);
+  int32_t numIndices = selection.Length();
+  // Iterate over the selection, counting up the messages in collapsed
+  // threads.
+  for (int32_t i = 0; i < numIndices; i++) {
+    if (m_flags[selection[i]] & nsMsgMessageFlags::Elided) {
+      int32_t collapsedCount;
+      ExpansionDelta(selection[i], &collapsedCount);
+      numSelectedIncludingCollapsed += collapsedCount;
+    }
+  }
+
+  *aNumSelected = numSelectedIncludingCollapsed;
+  return rv;
+}
+
+NS_IMETHODIMP
+nsMsgDBView::GetNumMsgsInView(int32_t* aNumMsgs) {
+  NS_ENSURE_ARG_POINTER(aNumMsgs);
+  return (m_folder) ? m_folder->GetTotalMessages(false, aNumMsgs)
+                    : NS_ERROR_FAILURE;
+}
+
+/**
+ * @note For the IMAP delete model, this applies to both deleting and
+ *       undeleting a message.
+ */
+NS_IMETHODIMP
+nsMsgDBView::GetMsgToSelectAfterDelete(nsMsgViewIndex* msgToSelectAfterDelete) {
+  NS_ENSURE_ARG_POINTER(msgToSelectAfterDelete);
+  *msgToSelectAfterDelete = nsMsgViewIndex_None;
+
+  bool isMultiSelect = false;
+  int32_t startFirstRange = nsMsgViewIndex_None;
+  int32_t endFirstRange = nsMsgViewIndex_None;
+  if (!mTreeSelection) {
+    // If we don't have a tree selection then we must be in stand alone mode.
+    // return the index of the current message key as the first selected index.
+    *msgToSelectAfterDelete = FindViewIndex(m_currentlyDisplayedMsgKey);
+  } else {
+    int32_t selectionCount;
+    int32_t startRange;
+    int32_t endRange;
+    nsresult rv = mTreeSelection->GetRangeCount(&selectionCount);
+    NS_ENSURE_SUCCESS(rv, rv);
+    for (int32_t i = 0; i < selectionCount; i++) {
+      rv = mTreeSelection->GetRangeAt(i, &startRange, &endRange);
+      NS_ENSURE_SUCCESS(rv, rv);
+
+      // Save off the first range in case we need it later.
+      if (i == 0) {
+        startFirstRange = startRange;
+        endFirstRange = endRange;
+      } else {
+        // If the tree selection is goofy (eg adjacent or overlapping ranges),
+        // complain about it, but don't try and cope.  Just live with the fact
+        // that one of the deleted messages is going to end up selected.
+        NS_WARNING_ASSERTION(
+            endFirstRange != startRange,
+            "goofy tree selection state: two ranges are adjacent!");
+      }
+
+      *msgToSelectAfterDelete =
+          std::min(*msgToSelectAfterDelete, (nsMsgViewIndex)startRange);
+    }
+
+    // Multiple selection either using Ctrl, Shift, or one of the affordances
+    // to select an entire thread.
+    isMultiSelect = (selectionCount > 1 || (endRange - startRange) > 0);
+  }
+
+  if (*msgToSelectAfterDelete == nsMsgViewIndex_None) return NS_OK;
+
+  nsCOMPtr<nsIMsgFolder> folder;
+  GetMsgFolder(getter_AddRefs(folder));
+  nsCOMPtr<nsIMsgImapMailFolder> imapFolder = do_QueryInterface(folder);
+  bool thisIsImapFolder = (imapFolder != nullptr);
+  // Need to update the imap-delete model, can change more than once in a
+  // session.
+  if (thisIsImapFolder) GetImapDeleteModel(nullptr);
+
+  // If mail.delete_matches_sort_order is true,
+  // for views sorted in descending order (newest at the top), make
+  // msgToSelectAfterDelete advance in the same direction as the sort order.
+  bool deleteMatchesSort = false;
+  if (m_sortOrder == nsMsgViewSortOrder::descending &&
+      *msgToSelectAfterDelete) {
+    nsresult rv;
+    nsCOMPtr<nsIPrefBranch> prefBranch(
+        do_GetService(NS_PREFSERVICE_CONTRACTID, &rv));
+    NS_ENSURE_SUCCESS(rv, rv);
+    prefBranch->GetBoolPref("mail.delete_matches_sort_order",
+                            &deleteMatchesSort);
+  }
+
+  if (mDeleteModel == nsMsgImapDeleteModels::IMAPDelete) {
+    if (isMultiSelect) {
+      if (deleteMatchesSort)
+        *msgToSelectAfterDelete = startFirstRange - 1;
+      else
+        *msgToSelectAfterDelete = endFirstRange + 1;
+    } else {
+      if (deleteMatchesSort)
+        *msgToSelectAfterDelete -= 1;
+      else
+        *msgToSelectAfterDelete += 1;
+    }
+  } else if (deleteMatchesSort) {
+    *msgToSelectAfterDelete -= 1;
+  }
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsMsgDBView::GetRemoveRowOnMoveOrDelete(bool* aRemoveRowOnMoveOrDelete) {
+  NS_ENSURE_ARG_POINTER(aRemoveRowOnMoveOrDelete);
+  nsCOMPtr<nsIMsgImapMailFolder> imapFolder = do_QueryInterface(m_folder);
+  if (!imapFolder) {
+    *aRemoveRowOnMoveOrDelete = true;
+    return NS_OK;
+  }
+
+  // Need to update the imap-delete model, can change more than once in a
+  // session.
+  GetImapDeleteModel(nullptr);
+
+  // Unlike the other imap delete models, "mark as deleted" does not remove
+  // rows on delete (or move).
+  *aRemoveRowOnMoveOrDelete =
+      (mDeleteModel != nsMsgImapDeleteModels::IMAPDelete);
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsMsgDBView::GetCurrentlyDisplayedMessage(
+    nsMsgViewIndex* currentlyDisplayedMessage) {
+  NS_ENSURE_ARG_POINTER(currentlyDisplayedMessage);
+  *currentlyDisplayedMessage = FindViewIndex(m_currentlyDisplayedMsgKey);
+  return NS_OK;
+}
+
+// If nothing selected, return an NS_ERROR.
+NS_IMETHODIMP
+nsMsgDBView::GetHdrForFirstSelectedMessage(nsIMsgDBHdr** hdr) {
+  NS_ENSURE_ARG_POINTER(hdr);
+
+  nsresult rv;
+  nsMsgKey key;
+  rv = GetKeyForFirstSelectedMessage(&key);
+  // Don't assert, it is legal for nothing to be selected.
+  if (NS_FAILED(rv)) return rv;
+
+  if (key == nsMsgKey_None) {
+    *hdr = nullptr;
+    return NS_OK;
+  }
+
+  if (!m_db) return NS_MSG_MESSAGE_NOT_FOUND;
+
+  rv = m_db->GetMsgHdrForKey(key, hdr);
+  NS_ENSURE_SUCCESS(rv, rv);
+  return NS_OK;
+}
+
+// If nothing selected, return an NS_ERROR.
+NS_IMETHODIMP
+nsMsgDBView::GetURIForFirstSelectedMessage(nsACString& uri) {
+  nsresult rv;
+  nsMsgViewIndex viewIndex;
+  rv = GetViewIndexForFirstSelectedMsg(&viewIndex);
+  // Don't assert, it is legal for nothing to be selected.
+  if (NS_FAILED(rv)) return rv;
+
+  return GetURIForViewIndex(viewIndex, uri);
+}
+
+NS_IMETHODIMP
+nsMsgDBView::OnDeleteCompleted(bool aSucceeded) {
+  if (m_deletingRows && aSucceeded) {
+    uint32_t numIndices = mIndicesToNoteChange.Length();
+    if (numIndices && (mTree || mJSTree)) {
+      if (numIndices > 1) mIndicesToNoteChange.Sort();
+
+      // The call to NoteChange() has to happen after we are done removing the
+      // keys as NoteChange() will call RowCountChanged() which will call our
+      // GetRowCount().
+      if (numIndices > 1) {
+        if (mTree) mTree->BeginUpdateBatch();
+        if (mJSTree) mJSTree->BeginUpdateBatch();
+      }
+
+      for (uint32_t i = 0; i < numIndices; i++)
+        NoteChange(mIndicesToNoteChange[i], -1,
+                   nsMsgViewNotificationCode::insertOrDelete);
+
+      if (numIndices > 1) {
+        if (mTree) mTree->EndUpdateBatch();
+        if (mJSTree) mJSTree->EndUpdateBatch();
+      }
+    }
+
+    mIndicesToNoteChange.Clear();
+  }
+
+  m_deletingRows = false;
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsMsgDBView::GetDb(nsIMsgDatabase** aDB) {
+  NS_ENSURE_ARG_POINTER(aDB);
+  NS_IF_ADDREF(*aDB = m_db);
+  return NS_OK;
+}
+
+bool nsMsgDBView::OfflineMsgSelected(
+    nsTArray<nsMsgViewIndex> const& selection) {
+  nsCOMPtr<nsIMsgLocalMailFolder> localFolder = do_QueryInterface(m_folder);
+  if (localFolder) {
+    return true;
+  }
+
+  for (nsMsgViewIndex viewIndex : selection) {
+    // For cross-folder saved searches, we need to check if any message
+    // is in a local folder.
+    if (!m_folder) {
+      nsCOMPtr<nsIMsgFolder> folder;
+      GetFolderForViewIndex(viewIndex, getter_AddRefs(folder));
+      nsCOMPtr<nsIMsgLocalMailFolder> localFolder = do_QueryInterface(folder);
+      if (localFolder) {
+        return true;
+      }
+    }
+
+    uint32_t flags = m_flags[viewIndex];
+    if ((flags & nsMsgMessageFlags::Offline)) {
+      return true;
+    }
+  }
+
+  return false;
+}
+
+bool nsMsgDBView::NonDummyMsgSelected(
+    nsTArray<nsMsgViewIndex> const& selection) {
+  bool includeCollapsedMsgs = OperateOnMsgsInCollapsedThreads();
+
+  for (nsMsgViewIndex viewIndex : selection) {
+    uint32_t flags = m_flags[viewIndex];
+    // We now treat having a collapsed dummy message selected as if
+    // the whole group was selected so we can apply commands to the group.
+    if (!(flags & MSG_VIEW_FLAG_DUMMY) ||
+        (flags & nsMsgMessageFlags::Elided && includeCollapsedMsgs)) {
+      return true;
+    }
+  }
+
+  return false;
+}
+
+NS_IMETHODIMP
+nsMsgDBView::GetViewIndexForFirstSelectedMsg(nsMsgViewIndex* aViewIndex) {
+  NS_ENSURE_ARG_POINTER(aViewIndex);
+  // If we don't have a tree selection we must be in stand alone mode...
+  if (!mTreeSelection) {
+    *aViewIndex = m_currentlyDisplayedViewIndex;
+    return NS_OK;
+  }
+
+  int32_t startRange;
+  int32_t endRange;
+  nsresult rv = mTreeSelection->GetRangeAt(0, &startRange, &endRange);
+  // Don't assert, it is legal for nothing to be selected.
+  if (NS_FAILED(rv)) return rv;
+
+  // Check that the first index is valid, it may not be if nothing is selected.
+  if (startRange < 0 || uint32_t(startRange) >= GetSize())
+    return NS_ERROR_UNEXPECTED;
+
+  *aViewIndex = startRange;
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsMsgDBView::GetKeyForFirstSelectedMessage(nsMsgKey* key) {
+  NS_ENSURE_ARG_POINTER(key);
+  // If we don't have a tree selection we must be in stand alone mode...
+  if (!mTreeSelection) {
+    *key = m_currentlyDisplayedMsgKey;
+    return NS_OK;
+  }
+
+  int32_t selectionCount;
+  mTreeSelection->GetRangeCount(&selectionCount);
+  if (selectionCount == 0) {
+    *key = nsMsgKey_None;
+    return NS_OK;
+  }
+
+  int32_t startRange;
+  int32_t endRange;
+  nsresult rv = mTreeSelection->GetRangeAt(0, &startRange, &endRange);
+  // Don't assert, it is legal for nothing to be selected.
+  if (NS_FAILED(rv)) return rv;
+
+  // Check that the first index is valid, it may not be if nothing is selected.
+  if (startRange < 0 || uint32_t(startRange) >= GetSize())
+    return NS_ERROR_UNEXPECTED;
+
+  if (m_flags[startRange] & MSG_VIEW_FLAG_DUMMY)
+    return NS_MSG_INVALID_DBVIEW_INDEX;
+
+  *key = m_keys[startRange];
+  return NS_OK;
+}
+
+nsCOMArray<nsIMsgFolder>* nsMsgDBView::GetFolders() { return nullptr; }
+
+nsresult nsMsgDBView::AdjustRowCount(int32_t rowCountBeforeSort,
+                                     int32_t rowCountAfterSort) {
+  int32_t rowChange = rowCountAfterSort - rowCountBeforeSort;
+
+  if (rowChange) {
+    // This is not safe to use when you have a selection.
+    // RowCountChanged() will call AdjustSelection().
+    uint32_t numSelected = 0;
+    GetNumSelected(&numSelected);
+    NS_ASSERTION(
+        numSelected == 0,
+        "it is not save to call AdjustRowCount() when you have a selection");
+
+    if (mTree) mTree->RowCountChanged(0, rowChange);
+    if (mJSTree) mJSTree->RowCountChanged(0, rowChange);
+  }
+
+  return NS_OK;
+}
+
+nsresult nsMsgDBView::GetImapDeleteModel(nsIMsgFolder* folder) {
+  nsresult rv = NS_OK;
+  nsCOMPtr<nsIMsgIncomingServer> server;
+  // For the search view.
+  if (folder)
+    folder->GetServer(getter_AddRefs(server));
+  else if (m_folder)
+    m_folder->GetServer(getter_AddRefs(server));
+
+  nsCOMPtr<nsIImapIncomingServer> imapServer = do_QueryInterface(server, &rv);
+  if (NS_SUCCEEDED(rv) && imapServer) imapServer->GetDeleteModel(&mDeleteModel);
+
+  return rv;
+}
+
+//
+// CanDrop
+//
+// Can't drop on the thread pane.
+//
+NS_IMETHODIMP
+nsMsgDBView::CanDrop(int32_t index, int32_t orient,
+                     mozilla::dom::DataTransfer* dataTransfer, bool* _retval) {
+  NS_ENSURE_ARG_POINTER(_retval);
+  *_retval = false;
+
+  return NS_OK;
+}
+
+//
+// Drop
+//
+// Can't drop on the thread pane.
+//
+NS_IMETHODIMP
+nsMsgDBView::Drop(int32_t row, int32_t orient,
+                  mozilla::dom::DataTransfer* dataTransfer) {
+  return NS_OK;
+}
+
+//
+// IsSorted
+//
+// ...
+//
+NS_IMETHODIMP
+nsMsgDBView::IsSorted(bool* _retval) {
+  *_retval = false;
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsMsgDBView::SelectFolderMsgByKey(nsIMsgFolder* aFolder, nsMsgKey aKey) {
+  NS_ENSURE_ARG_POINTER(aFolder);
+  if (aKey == nsMsgKey_None) return NS_ERROR_FAILURE;
+
+  // This is OK for non search views.
+
+  nsMsgViewIndex viewIndex = FindKey(aKey, true /* expand */);
+
+  if (mTree) mTreeSelection->SetCurrentIndex(viewIndex);
+
+  // Make sure the current message is once again visible in the thread pane
+  // so we don't have to go search for it in the thread pane.
+  if (mTree && viewIndex != nsMsgViewIndex_None) {
+    mTreeSelection->Select(viewIndex);
+    mTree->EnsureRowIsVisible(viewIndex);
+  }
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsMsgDBView::SelectMsgByKey(nsMsgKey aKey) {
+  NS_ASSERTION(aKey != nsMsgKey_None, "bad key");
+  if (aKey == nsMsgKey_None) return NS_OK;
+
+  // Use SaveAndClearSelection()
+  // and RestoreSelection() so that we'll clear the current selection
+  // but pass in a different key array so that we'll
+  // select (and load) the desired message.
+
+  AutoTArray<nsMsgKey, 1> preservedSelection;
+  nsresult rv = SaveAndClearSelection(nullptr, preservedSelection);
+  NS_ENSURE_SUCCESS(rv, rv);
+
+  // Now, restore our desired selection.
+  AutoTArray<nsMsgKey, 1> keyArray;
+  keyArray.AppendElement(aKey);
+
+  // If the key was not found
+  // (this can happen with "remember last selected message")
+  // nothing will be selected.
+  rv = RestoreSelection(aKey, keyArray);
+  NS_ENSURE_SUCCESS(rv, rv);
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsMsgDBView::CloneDBView(nsIMessenger* aMessengerInstance,
+                         nsIMsgWindow* aMsgWindow,
+                         nsIMsgDBViewCommandUpdater* aCmdUpdater,
+                         nsIMsgDBView** _retval) {
+  nsMsgDBView* newMsgDBView = new nsMsgDBView();
+
+  nsresult rv =
+      CopyDBView(newMsgDBView, aMessengerInstance, aMsgWindow, aCmdUpdater);
+  NS_ENSURE_SUCCESS(rv, rv);
+
+  NS_IF_ADDREF(*_retval = newMsgDBView);
+  return NS_OK;
+}
+
+nsresult nsMsgDBView::CopyDBView(nsMsgDBView* aNewMsgDBView,
+                                 nsIMessenger* aMessengerInstance,
+                                 nsIMsgWindow* aMsgWindow,
+                                 nsIMsgDBViewCommandUpdater* aCmdUpdater) {
+  NS_ENSURE_ARG_POINTER(aNewMsgDBView);
+  if (aMsgWindow) {
+    aNewMsgDBView->mMsgWindowWeak = do_GetWeakReference(aMsgWindow);
+    aMsgWindow->SetOpenFolder(m_viewFolder ? m_viewFolder : m_folder);
+  }
+
+  aNewMsgDBView->mMessengerWeak = do_GetWeakReference(aMessengerInstance);
+  aNewMsgDBView->mCommandUpdater = do_GetWeakReference(aCmdUpdater);
+  aNewMsgDBView->m_folder = m_folder;
+  aNewMsgDBView->m_viewFlags = m_viewFlags;
+  aNewMsgDBView->m_sortOrder = m_sortOrder;
+  aNewMsgDBView->m_sortType = m_sortType;
+  aNewMsgDBView->m_curCustomColumn = m_curCustomColumn;
+  aNewMsgDBView->m_secondarySort = m_secondarySort;
+  aNewMsgDBView->m_secondarySortOrder = m_secondarySortOrder;
+  aNewMsgDBView->m_secondaryCustomColumn = m_secondaryCustomColumn;
+  aNewMsgDBView->m_db = m_db;
+  if (m_db) aNewMsgDBView->m_db->AddListener(aNewMsgDBView);
+
+  aNewMsgDBView->mIsNews = mIsNews;
+  aNewMsgDBView->mIsRss = mIsRss;
+  aNewMsgDBView->mIsXFVirtual = mIsXFVirtual;
+  aNewMsgDBView->mShowSizeInLines = mShowSizeInLines;
+  aNewMsgDBView->mDeleteModel = mDeleteModel;
+  aNewMsgDBView->m_flags = m_flags.Clone();
+  aNewMsgDBView->m_levels = m_levels.Clone();
+  aNewMsgDBView->m_keys = m_keys.Clone();
+
+  aNewMsgDBView->m_customColumnHandlerIDs = m_customColumnHandlerIDs.Clone();
+  aNewMsgDBView->m_customColumnHandlers.AppendObjects(m_customColumnHandlers);
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsMsgDBView::GetSearchSession(nsIMsgSearchSession** aSession) {
+  NS_ASSERTION(false, "should be overridden by child class");
+  return NS_ERROR_NOT_IMPLEMENTED;
+}
+
+NS_IMETHODIMP
+nsMsgDBView::SetSearchSession(nsIMsgSearchSession* aSession) {
+  NS_ASSERTION(false, "should be overridden by child class");
+  return NS_ERROR_NOT_IMPLEMENTED;
+}
+
+NS_IMETHODIMP
+nsMsgDBView::GetSupportsThreading(bool* aResult) {
+  NS_ENSURE_ARG_POINTER(aResult);
+  *aResult = true;
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsMsgDBView::FindIndexFromKey(nsMsgKey aMsgKey, bool aExpand,
+                              nsMsgViewIndex* aIndex) {
+  NS_ENSURE_ARG_POINTER(aIndex);
+  *aIndex = FindKey(aMsgKey, aExpand);
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsMsgDBView::FindIndexOfMsgHdr(nsIMsgDBHdr* aMsgHdr, bool aExpand,
+                               nsMsgViewIndex* aIndex) {
+  NS_ENSURE_ARG(aMsgHdr);
+  NS_ENSURE_ARG_POINTER(aIndex);
+
+  if (m_viewFlags & nsMsgViewFlagsType::kThreadedDisplay) {
+    nsMsgViewIndex threadIndex = ThreadIndexOfMsgHdr(aMsgHdr);
+    if (threadIndex != nsMsgViewIndex_None) {
+      if (aExpand && (m_flags[threadIndex] & nsMsgMessageFlags::Elided))
+        ExpandByIndex(threadIndex, nullptr);
+
+      *aIndex = FindHdr(aMsgHdr, threadIndex);
+    } else {
+      *aIndex = nsMsgViewIndex_None;
+    }
+  } else {
+    *aIndex = FindHdr(aMsgHdr);
+  }
+
+  return NS_OK;
+}
+
+static void getDateFormatPref(nsIPrefBranch* _prefBranch,
+                              const char* _prefLocalName,
+                              nsDateFormatSelectorComm& _format) {
+  // Read.
+  int32_t nFormatSetting(0);
+  nsresult result = _prefBranch->GetIntPref(_prefLocalName, &nFormatSetting);
+  if (NS_SUCCEEDED(result)) {
+    // Translate.
+    nsDateFormatSelectorComm res;
+    res = static_cast<nsDateFormatSelectorComm>(nFormatSetting);
+    // Transfer if valid.
+    if (res >= kDateFormatNone && res <= kDateFormatShort)
+      _format = res;
+    else if (res == kDateFormatWeekday)
+      _format = res;
+  }
+}
+
+nsresult nsMsgDBView::InitDisplayFormats() {
+  m_dateFormatsInitialized = true;
+
+  nsresult rv = NS_OK;
+  nsCOMPtr<nsIPrefService> prefs =
+      do_GetService(NS_PREFSERVICE_CONTRACTID, &rv);
+  NS_ENSURE_SUCCESS(rv, rv);
+  nsCOMPtr<nsIPrefBranch> dateFormatPrefs;
+  rv = prefs->GetBranch("mail.ui.display.dateformat.",
+                        getter_AddRefs(dateFormatPrefs));
+  NS_ENSURE_SUCCESS(rv, rv);
+
+  getDateFormatPref(dateFormatPrefs, "default", m_dateFormatDefault);
+  getDateFormatPref(dateFormatPrefs, "thisweek", m_dateFormatThisWeek);
+  getDateFormatPref(dateFormatPrefs, "today", m_dateFormatToday);
+  return rv;
+}
+
+void nsMsgDBView::SetMRUTimeForFolder(nsIMsgFolder* folder) {
+  uint32_t seconds;
+  PRTime2Seconds(PR_Now(), &seconds);
+  nsAutoCString nowStr;
+  nowStr.AppendInt(seconds);
+  folder->SetStringProperty(MRU_TIME_PROPERTY, nowStr);
+}
+
+nsMsgDBView::nsMsgViewHdrEnumerator::nsMsgViewHdrEnumerator(nsMsgDBView* view) {
+  // We need to clone the view because the caller may clear the
+  // current view immediately. It also makes it easier to expand all
+  // if we're working on a copy.
+  nsCOMPtr<nsIMsgDBView> clonedView;
+  view->CloneDBView(nullptr, nullptr, nullptr, getter_AddRefs(clonedView));
+  m_view = static_cast<nsMsgDBView*>(clonedView.get());
+  // Make sure we enumerate over collapsed threads by expanding all.
+  m_view->ExpandAll();
+  m_curHdrIndex = 0;
+}
+
+nsMsgDBView::nsMsgViewHdrEnumerator::~nsMsgViewHdrEnumerator() {
+  if (m_view) m_view->Close();
+}
+
+NS_IMETHODIMP
+nsMsgDBView::nsMsgViewHdrEnumerator::GetNext(nsIMsgDBHdr** aItem) {
+  NS_ENSURE_ARG_POINTER(aItem);
+
+  if (m_curHdrIndex >= m_view->GetSize()) return NS_ERROR_FAILURE;
+
+  // Ignore dummy header. We won't have empty groups, so
+  // we know the view index is good.
+  if (m_view->m_flags[m_curHdrIndex] & MSG_VIEW_FLAG_DUMMY) ++m_curHdrIndex;
+
+  nsCOMPtr<nsIMsgDBHdr> nextHdr;
+
+  nsresult rv =
+      m_view->GetMsgHdrForViewIndex(m_curHdrIndex++, getter_AddRefs(nextHdr));
+  nextHdr.forget(aItem);
+  return rv;
+}
+
+NS_IMETHODIMP
+nsMsgDBView::nsMsgViewHdrEnumerator::HasMoreElements(bool* aResult) {
+  NS_ENSURE_ARG_POINTER(aResult);
+  *aResult = m_curHdrIndex < m_view->GetSize();
+  return NS_OK;
+}
+
+nsresult nsMsgDBView::GetViewEnumerator(nsIMsgEnumerator** enumerator) {
+  NS_IF_ADDREF(*enumerator = new nsMsgViewHdrEnumerator(this));
+  return (*enumerator) ? NS_OK : NS_ERROR_OUT_OF_MEMORY;
+}
+
+nsresult nsMsgDBView::GetDBForHeader(nsIMsgDBHdr* msgHdr, nsIMsgDatabase** db) {
+  nsCOMPtr<nsIMsgFolder> folder;
+  nsresult rv = msgHdr->GetFolder(getter_AddRefs(folder));
+  NS_ENSURE_SUCCESS(rv, rv);
+  return folder->GetMsgDatabase(db);
+}
+
+/**
+ * Determine whether junk commands should be enabled on this view.
+ * Junk commands are always enabled for mail. For nntp and rss, they
+ * may be selectively enabled using an inherited folder property.
+ *
+ * @param  aViewIndex  view index of the message to check
+ * @return             true if junk controls should be enabled
+ */
+bool nsMsgDBView::JunkControlsEnabled(nsMsgViewIndex aViewIndex) {
+  // For normal mail, junk commands are always enabled.
+  if (!(mIsNews || mIsRss || mIsXFVirtual)) return true;
+
+  // We need to check per message or folder.
+  nsCOMPtr<nsIMsgFolder> folder = m_folder;
+  if (!folder && IsValidIndex(aViewIndex))
+    GetFolderForViewIndex(aViewIndex, getter_AddRefs(folder));
+
+  if (folder) {
+    // Check if this is a mail message in search folders.
+    if (mIsXFVirtual) {
+      nsCOMPtr<nsIMsgIncomingServer> server;
+      folder->GetServer(getter_AddRefs(server));
+      nsAutoCString type;
+      if (server) server->GetType(type);
+
+      if (!(type.LowerCaseEqualsLiteral("nntp") ||
+            type.LowerCaseEqualsLiteral("rss")))
+        return true;
+    }
+
+    // For rss and news, check the inherited folder property.
+    nsAutoCString junkEnableOverride;
+    folder->GetInheritedStringProperty("dobayes.mailnews@mozilla.org#junk",
+                                       junkEnableOverride);
+    if (junkEnableOverride.EqualsLiteral("true")) return true;
+  }
+
+  return false;
+}