Adding upstream version 115.7.0esr.upstream/115.7.0esrupstream

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

1 files changed, 4259 insertions, 0 deletions

diff --git a/widget/cocoa/nsCocoaWindow.mm b/widget/cocoa/nsCocoaWindow.mm
new file mode 100644
index 0000000000..c3c246cc74
--- /dev/null
+++ b/widget/cocoa/nsCocoaWindow.mm
@@ -0,0 +1,4259 @@
+/* -*- Mode: Objective-C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=2 et sw=2 tw=80: */
+/* 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 "nsCocoaWindow.h"
+
+#include "AppearanceOverride.h"
+#include "NativeKeyBindings.h"
+#include "ScreenHelperCocoa.h"
+#include "TextInputHandler.h"
+#include "nsCocoaUtils.h"
+#include "nsObjCExceptions.h"
+#include "nsCOMPtr.h"
+#include "nsWidgetsCID.h"
+#include "nsIRollupListener.h"
+#include "nsChildView.h"
+#include "nsWindowMap.h"
+#include "nsAppShell.h"
+#include "nsIAppShellService.h"
+#include "nsIBaseWindow.h"
+#include "nsIInterfaceRequestorUtils.h"
+#include "nsIAppWindow.h"
+#include "nsToolkit.h"
+#include "nsTouchBarNativeAPIDefines.h"
+#include "nsPIDOMWindow.h"
+#include "nsThreadUtils.h"
+#include "nsMenuBarX.h"
+#include "nsMenuUtilsX.h"
+#include "nsStyleConsts.h"
+#include "nsNativeThemeColors.h"
+#include "nsNativeThemeCocoa.h"
+#include "nsChildView.h"
+#include "nsCocoaFeatures.h"
+#include "nsIScreenManager.h"
+#include "nsIWidgetListener.h"
+#include "SDKDeclarations.h"
+#include "VibrancyManager.h"
+#include "nsPresContext.h"
+#include "nsDocShell.h"
+
+#include "gfxPlatform.h"
+#include "qcms.h"
+
+#include "mozilla/AutoRestore.h"
+#include "mozilla/BasicEvents.h"
+#include "mozilla/dom/Document.h"
+#include "mozilla/Maybe.h"
+#include "mozilla/NativeKeyBindingsType.h"
+#include "mozilla/Preferences.h"
+#include "mozilla/PresShell.h"
+#include "mozilla/ScopeExit.h"
+#include "mozilla/StaticPrefs_gfx.h"
+#include "mozilla/StaticPrefs_widget.h"
+#include "mozilla/WritingModes.h"
+#include "mozilla/layers/CompositorBridgeChild.h"
+#include "mozilla/widget/Screen.h"
+#include <algorithm>
+
+namespace mozilla {
+namespace layers {
+class LayerManager;
+}  // namespace layers
+}  // namespace mozilla
+using namespace mozilla::layers;
+using namespace mozilla::widget;
+using namespace mozilla;
+
+int32_t gXULModalLevel = 0;
+
+// In principle there should be only one app-modal window at any given time.
+// But sometimes, despite our best efforts, another window appears above the
+// current app-modal window.  So we need to keep a linked list of app-modal
+// windows.  (A non-sheet window that appears above an app-modal window is
+// also made app-modal.)  See nsCocoaWindow::SetModal().
+nsCocoaWindowList* gGeckoAppModalWindowList = NULL;
+
+BOOL sTouchBarIsInitialized = NO;
+
+// defined in nsMenuBarX.mm
+extern NSMenu* sApplicationMenu;  // Application menu shared by all menubars
+
+// defined in nsChildView.mm
+extern BOOL gSomeMenuBarPainted;
+
+extern "C" {
+// CGSPrivate.h
+typedef NSInteger CGSConnection;
+typedef NSUInteger CGSSpaceID;
+typedef NSInteger CGSWindow;
+typedef enum {
+  kCGSSpaceIncludesCurrent = 1 << 0,
+  kCGSSpaceIncludesOthers = 1 << 1,
+  kCGSSpaceIncludesUser = 1 << 2,
+
+  kCGSAllSpacesMask = kCGSSpaceIncludesCurrent | kCGSSpaceIncludesOthers | kCGSSpaceIncludesUser
+} CGSSpaceMask;
+static NSString* const CGSSpaceIDKey = @"ManagedSpaceID";
+static NSString* const CGSSpacesKey = @"Spaces";
+extern CGSConnection _CGSDefaultConnection(void);
+extern CGError CGSSetWindowTransform(CGSConnection cid, CGSWindow wid, CGAffineTransform transform);
+}
+
+#define NS_APPSHELLSERVICE_CONTRACTID "@mozilla.org/appshell/appShellService;1"
+
+NS_IMPL_ISUPPORTS_INHERITED(nsCocoaWindow, Inherited, nsPIWidgetCocoa)
+
+// A note on testing to see if your object is a sheet...
+// |mWindowType == WindowType::Sheet| is true if your gecko nsIWidget is a sheet
+// widget - whether or not the sheet is showing. |[mWindow isSheet]| will return
+// true *only when the sheet is actually showing*. Choose your test wisely.
+
+static void RollUpPopups(
+    nsIRollupListener::AllowAnimations aAllowAnimations = nsIRollupListener::AllowAnimations::Yes) {
+  nsIRollupListener* rollupListener = nsBaseWidget::GetActiveRollupListener();
+  NS_ENSURE_TRUE_VOID(rollupListener);
+
+  if (rollupListener->RollupNativeMenu()) {
+    return;
+  }
+
+  nsCOMPtr<nsIWidget> rollupWidget = rollupListener->GetRollupWidget();
+  if (!rollupWidget) {
+    return;
+  }
+  nsIRollupListener::RollupOptions options{0, nsIRollupListener::FlushViews::Yes, nullptr,
+                                           aAllowAnimations};
+  rollupListener->Rollup(options);
+}
+
+nsCocoaWindow::nsCocoaWindow()
+    : mParent(nullptr),
+      mAncestorLink(nullptr),
+      mWindow(nil),
+      mDelegate(nil),
+      mSheetWindowParent(nil),
+      mPopupContentView(nil),
+      mFullscreenTransitionAnimation(nil),
+      mShadowStyle(StyleWindowShadow::Default),
+      mBackingScaleFactor(0.0),
+      mAnimationType(nsIWidget::eGenericWindowAnimation),
+      mWindowMadeHere(false),
+      mSheetNeedsShow(false),
+      mSizeMode(nsSizeMode_Normal),
+      mInFullScreenMode(false),
+      mInNativeFullScreenMode(false),
+      mIgnoreOcclusionCount(0),
+      mHasStartedNativeFullscreen(false),
+      mModal(false),
+      mFakeModal(false),
+      mIsAnimationSuppressed(false),
+      mInReportMoveEvent(false),
+      mInResize(false),
+      mWindowTransformIsIdentity(true),
+      mAlwaysOnTop(false),
+      mAspectRatioLocked(false),
+      mNumModalDescendents(0),
+      mWindowAnimationBehavior(NSWindowAnimationBehaviorDefault),
+      mWasShown(false) {
+  // Disable automatic tabbing. We need to do this before we
+  // orderFront any of our windows.
+  [NSWindow setAllowsAutomaticWindowTabbing:NO];
+}
+
+void nsCocoaWindow::DestroyNativeWindow() {
+  NS_OBJC_BEGIN_TRY_IGNORE_BLOCK;
+
+  if (!mWindow) return;
+
+  [mWindow releaseJSObjects];
+  // We want to unhook the delegate here because we don't want events
+  // sent to it after this object has been destroyed.
+  [mWindow setDelegate:nil];
+  [mWindow close];
+  mWindow = nil;
+  [mDelegate autorelease];
+
+  NS_OBJC_END_TRY_IGNORE_BLOCK;
+}
+
+nsCocoaWindow::~nsCocoaWindow() {
+  NS_OBJC_BEGIN_TRY_IGNORE_BLOCK;
+
+  // Notify the children that we're gone.  Popup windows (e.g. tooltips) can
+  // have nsChildView children.  'kid' is an nsChildView object if and only if
+  // its 'type' is 'WindowType::Child'.
+  // childView->ResetParent() can change our list of children while it's
+  // being iterated, so the way we iterate the list must allow for this.
+  for (nsIWidget* kid = mLastChild; kid;) {
+    WindowType kidType = kid->GetWindowType();
+    if (kidType == WindowType::Child) {
+      nsChildView* childView = static_cast<nsChildView*>(kid);
+      kid = kid->GetPrevSibling();
+      childView->ResetParent();
+    } else {
+      nsCocoaWindow* childWindow = static_cast<nsCocoaWindow*>(kid);
+      childWindow->mParent = nullptr;
+      childWindow->mAncestorLink = mAncestorLink;
+      kid = kid->GetPrevSibling();
+    }
+  }
+
+  if (mWindow && mWindowMadeHere) {
+    DestroyNativeWindow();
+  }
+
+  NS_IF_RELEASE(mPopupContentView);
+
+  // Deal with the possiblity that we're being destroyed while running modal.
+  if (mModal) {
+    NS_WARNING("Widget destroyed while running modal!");
+    --gXULModalLevel;
+    NS_ASSERTION(gXULModalLevel >= 0, "Weirdness setting modality!");
+  }
+
+  NS_OBJC_END_TRY_IGNORE_BLOCK;
+}
+
+// Find the screen that overlaps aRect the most,
+// if none are found default to the mainScreen.
+static NSScreen* FindTargetScreenForRect(const DesktopIntRect& aRect) {
+  NSScreen* targetScreen = [NSScreen mainScreen];
+  NSEnumerator* screenEnum = [[NSScreen screens] objectEnumerator];
+  int largestIntersectArea = 0;
+  while (NSScreen* screen = [screenEnum nextObject]) {
+    DesktopIntRect screenRect = nsCocoaUtils::CocoaRectToGeckoRect([screen visibleFrame]);
+    screenRect = screenRect.Intersect(aRect);
+    int area = screenRect.width * screenRect.height;
+    if (area > largestIntersectArea) {
+      largestIntersectArea = area;
+      targetScreen = screen;
+    }
+  }
+  return targetScreen;
+}
+
+// fits the rect to the screen that contains the largest area of it,
+// or to aScreen if a screen is passed in
+// NB: this operates with aRect in desktop pixels
+static void FitRectToVisibleAreaForScreen(DesktopIntRect& aRect, NSScreen* aScreen) {
+  if (!aScreen) {
+    aScreen = FindTargetScreenForRect(aRect);
+  }
+
+  DesktopIntRect screenBounds = nsCocoaUtils::CocoaRectToGeckoRect([aScreen visibleFrame]);
+
+  if (aRect.width > screenBounds.width) {
+    aRect.width = screenBounds.width;
+  }
+  if (aRect.height > screenBounds.height) {
+    aRect.height = screenBounds.height;
+  }
+
+  if (aRect.x - screenBounds.x + aRect.width > screenBounds.width) {
+    aRect.x += screenBounds.width - (aRect.x - screenBounds.x + aRect.width);
+  }
+  if (aRect.y - screenBounds.y + aRect.height > screenBounds.height) {
+    aRect.y += screenBounds.height - (aRect.y - screenBounds.y + aRect.height);
+  }
+
+  // If the left/top edge of the window is off the screen in either direction,
+  // then set the window to start at the left/top edge of the screen.
+  if (aRect.x < screenBounds.x || aRect.x > (screenBounds.x + screenBounds.width)) {
+    aRect.x = screenBounds.x;
+  }
+  if (aRect.y < screenBounds.y || aRect.y > (screenBounds.y + screenBounds.height)) {
+    aRect.y = screenBounds.y;
+  }
+}
+
+DesktopToLayoutDeviceScale ParentBackingScaleFactor(nsIWidget* aParent, NSView* aParentView) {
+  if (aParent) {
+    return aParent->GetDesktopToDeviceScale();
+  }
+  NSWindow* parentWindow = [aParentView window];
+  if (parentWindow) {
+    return DesktopToLayoutDeviceScale([parentWindow backingScaleFactor]);
+  }
+  return DesktopToLayoutDeviceScale(1.0);
+}
+
+// Returns the screen rectangle for the given widget.
+// Child widgets are positioned relative to this rectangle.
+// Exactly one of the arguments must be non-null.
+static DesktopRect GetWidgetScreenRectForChildren(nsIWidget* aWidget, NSView* aView) {
+  if (aWidget) {
+    mozilla::DesktopToLayoutDeviceScale scale = aWidget->GetDesktopToDeviceScale();
+    if (aWidget->GetWindowType() == WindowType::Child) {
+      return aWidget->GetScreenBounds() / scale;
+    }
+    return aWidget->GetClientBounds() / scale;
+  }
+
+  MOZ_RELEASE_ASSERT(aView);
+
+  // 1. Transform the view rect into window coords.
+  // The returned rect is in "origin bottom-left" coordinates.
+  NSRect rectInWindowCoordinatesOBL = [aView convertRect:[aView bounds] toView:nil];
+
+  // 2. Turn the window-coord rect into screen coords, still origin bottom-left.
+  NSRect rectInScreenCoordinatesOBL =
+      [[aView window] convertRectToScreen:rectInWindowCoordinatesOBL];
+
+  // 3. Convert the NSRect to a DesktopRect. This will convert to coordinates
+  // with the origin in the top left corner of the primary screen.
+  return DesktopRect(nsCocoaUtils::CocoaRectToGeckoRect(rectInScreenCoordinatesOBL));
+}
+
+// aRect here is specified in desktop pixels
+//
+// For child windows (where either aParent or aNativeParent is non-null),
+// aRect.{x,y} are offsets from the origin of the parent window and not an
+// absolute position.
+nsresult nsCocoaWindow::Create(nsIWidget* aParent, nsNativeWidget aNativeParent,
+                               const DesktopIntRect& aRect, widget::InitData* aInitData) {
+  NS_OBJC_BEGIN_TRY_BLOCK_RETURN;
+
+  // Because the hidden window is created outside of an event loop,
+  // we have to provide an autorelease pool (see bug 559075).
+  nsAutoreleasePool localPool;
+
+  DesktopIntRect newBounds = aRect;
+  FitRectToVisibleAreaForScreen(newBounds, nullptr);
+
+  // Set defaults which can be overriden from aInitData in BaseCreate
+  mWindowType = WindowType::TopLevel;
+  mBorderStyle = BorderStyle::Default;
+
+  // Ensure that the toolkit is created.
+  nsToolkit::GetToolkit();
+
+  Inherited::BaseCreate(aParent, aInitData);
+
+  mParent = aParent;
+  mAncestorLink = aParent;
+  mAlwaysOnTop = aInitData->mAlwaysOnTop;
+
+  // If we have a parent widget, the new widget will be offset from the
+  // parent widget by aRect.{x,y}. Otherwise, we'll use aRect for the
+  // new widget coordinates.
+  DesktopIntPoint parentOrigin;
+
+  // Do we have a parent widget?
+  if (aParent || aNativeParent) {
+    DesktopRect parentDesktopRect = GetWidgetScreenRectForChildren(aParent, (NSView*)aNativeParent);
+    parentOrigin = gfx::RoundedToInt(parentDesktopRect.TopLeft());
+  }
+
+  DesktopIntRect widgetRect = aRect + parentOrigin;
+
+  nsresult rv = CreateNativeWindow(nsCocoaUtils::GeckoRectToCocoaRect(widgetRect), mBorderStyle,
+                                   false, aInitData->mIsPrivate);
+  NS_ENSURE_SUCCESS(rv, rv);
+
+  if (mWindowType == WindowType::Popup) {
+    // now we can convert widgetRect to device pixels for the window we created,
+    // as the child view expects a rect expressed in the dev pix of its parent
+    LayoutDeviceIntRect devRect = RoundedToInt(newBounds * GetDesktopToDeviceScale());
+    return CreatePopupContentView(devRect, aInitData);
+  }
+
+  mIsAnimationSuppressed = aInitData->mIsAnimationSuppressed;
+
+  return NS_OK;
+
+  NS_OBJC_END_TRY_BLOCK_RETURN(NS_ERROR_FAILURE);
+}
+
+nsresult nsCocoaWindow::Create(nsIWidget* aParent, nsNativeWidget aNativeParent,
+                               const LayoutDeviceIntRect& aRect, widget::InitData* aInitData) {
+  DesktopIntRect desktopRect =
+      RoundedToInt(aRect / ParentBackingScaleFactor(aParent, (NSView*)aNativeParent));
+  return Create(aParent, aNativeParent, desktopRect, aInitData);
+}
+
+static unsigned int WindowMaskForBorderStyle(BorderStyle aBorderStyle) {
+  bool allOrDefault = (aBorderStyle == BorderStyle::All || aBorderStyle == BorderStyle::Default);
+
+  /* Apple's docs on NSWindow styles say that "a window's style mask should
+   * include NSWindowStyleMaskTitled if it includes any of the others [besides
+   * NSWindowStyleMaskBorderless]".  This implies that a borderless window
+   * shouldn't have any other styles than NSWindowStyleMaskBorderless.
+   */
+  if (!allOrDefault && !(aBorderStyle & BorderStyle::Title)) {
+    if (aBorderStyle & BorderStyle::Minimize) {
+      /* It appears that at a minimum, borderless windows can be miniaturizable,
+       * effectively contradicting some of Apple's documentation referenced
+       * above. One such exception is the screen share indicator, see
+       * bug 1742877.
+       */
+      return NSWindowStyleMaskBorderless | NSWindowStyleMaskMiniaturizable;
+    }
+    return NSWindowStyleMaskBorderless;
+  }
+
+  unsigned int mask = NSWindowStyleMaskTitled;
+  if (allOrDefault || aBorderStyle & BorderStyle::Close) {
+    mask |= NSWindowStyleMaskClosable;
+  }
+  if (allOrDefault || aBorderStyle & BorderStyle::Minimize) {
+    mask |= NSWindowStyleMaskMiniaturizable;
+  }
+  if (allOrDefault || aBorderStyle & BorderStyle::ResizeH) {
+    mask |= NSWindowStyleMaskResizable;
+  }
+
+  return mask;
+}
+
+// If aRectIsFrameRect, aRect specifies the frame rect of the new window.
+// Otherwise, aRect.x/y specify the position of the window's frame relative to
+// the bottom of the menubar and aRect.width/height specify the size of the
+// content rect.
+nsresult nsCocoaWindow::CreateNativeWindow(const NSRect& aRect, BorderStyle aBorderStyle,
+                                           bool aRectIsFrameRect, bool aIsPrivateBrowsing) {
+  NS_OBJC_BEGIN_TRY_BLOCK_RETURN;
+
+  // We default to NSWindowStyleMaskBorderless, add features if needed.
+  unsigned int features = NSWindowStyleMaskBorderless;
+
+  // Configure the window we will create based on the window type.
+  switch (mWindowType) {
+    case WindowType::Invisible:
+    case WindowType::Child:
+      break;
+    case WindowType::Popup:
+      if (aBorderStyle != BorderStyle::Default && mBorderStyle & BorderStyle::Title) {
+        features |= NSWindowStyleMaskTitled;
+        if (aBorderStyle & BorderStyle::Close) {
+          features |= NSWindowStyleMaskClosable;
+        }
+      }
+      break;
+    case WindowType::TopLevel:
+    case WindowType::Dialog:
+      features = WindowMaskForBorderStyle(aBorderStyle);
+      break;
+    case WindowType::Sheet:
+      if (mParent->GetWindowType() != WindowType::Invisible &&
+          aBorderStyle & BorderStyle::ResizeH) {
+        features = NSWindowStyleMaskResizable;
+      } else {
+        features = NSWindowStyleMaskMiniaturizable;
+      }
+      features |= NSWindowStyleMaskTitled;
+      break;
+    default:
+      NS_ERROR("Unhandled window type!");
+      return NS_ERROR_FAILURE;
+  }
+
+  NSRect contentRect;
+
+  if (aRectIsFrameRect) {
+    contentRect = [NSWindow contentRectForFrameRect:aRect styleMask:features];
+  } else {
+    /*
+     * We pass a content area rect to initialize the native Cocoa window. The
+     * content rect we give is the same size as the size we're given by gecko.
+     * The origin we're given for non-popup windows is moved down by the height
+     * of the menu bar so that an origin of (0,100) from gecko puts the window
+     * 100 pixels below the top of the available desktop area. We also move the
+     * origin down by the height of a title bar if it exists. This is so the
+     * origin that gecko gives us for the top-left of  the window turns out to
+     * be the top-left of the window we create. This is how it was done in
+     * Carbon. If it ought to be different we'll probably need to look at all
+     * the callers.
+     *
+     * Note: This means that if you put a secondary screen on top of your main
+     * screen and open a window in the top screen, it'll be incorrectly shifted
+     * down by the height of the menu bar. Same thing would happen in Carbon.
+     *
+     * Note: If you pass a rect with 0,0 for an origin, the window ends up in a
+     * weird place for some reason. This stops that without breaking popups.
+     */
+    // Compensate for difference between frame and content area height (e.g. title bar).
+    NSRect newWindowFrame = [NSWindow frameRectForContentRect:aRect styleMask:features];
+
+    contentRect = aRect;
+    contentRect.origin.y -= (newWindowFrame.size.height - aRect.size.height);
+
+    if (mWindowType != WindowType::Popup) contentRect.origin.y -= [[NSApp mainMenu] menuBarHeight];
+  }
+
+  // NSLog(@"Top-level window being created at Cocoa rect: %f, %f, %f, %f\n",
+  //       rect.origin.x, rect.origin.y, rect.size.width, rect.size.height);
+
+  Class windowClass = [BaseWindow class];
+  // If we have a titlebar on a top-level window, we want to be able to control the
+  // titlebar color (for unified windows), so use the special ToolbarWindow class.
+  // Note that we need to check the window type because we mark sheets as
+  // having titlebars.
+  if ((mWindowType == WindowType::TopLevel || mWindowType == WindowType::Dialog) &&
+      (features & NSWindowStyleMaskTitled))
+    windowClass = [ToolbarWindow class];
+  // If we're a popup window we need to use the PopupWindow class.
+  else if (mWindowType == WindowType::Popup)
+    windowClass = [PopupWindow class];
+  // If we're a non-popup borderless window we need to use the
+  // BorderlessWindow class.
+  else if (features == NSWindowStyleMaskBorderless)
+    windowClass = [BorderlessWindow class];
+
+  // Create the window
+  mWindow = [[windowClass alloc] initWithContentRect:contentRect
+                                           styleMask:features
+                                             backing:NSBackingStoreBuffered
+                                               defer:YES];
+
+  // Make sure that window titles don't leak to disk in private browsing mode
+  // due to macOS' resume feature.
+  [mWindow setRestorable:!aIsPrivateBrowsing];
+  if (aIsPrivateBrowsing) {
+    [mWindow disableSnapshotRestoration];
+  }
+
+  // setup our notification delegate. Note that setDelegate: does NOT retain.
+  mDelegate = [[WindowDelegate alloc] initWithGeckoWindow:this];
+  [mWindow setDelegate:mDelegate];
+
+  // Make sure that the content rect we gave has been honored.
+  NSRect wantedFrame = [mWindow frameRectForChildViewRect:contentRect];
+  if (!NSEqualRects([mWindow frame], wantedFrame)) {
+    // This can happen when the window is not on the primary screen.
+    [mWindow setFrame:wantedFrame display:NO];
+  }
+  UpdateBounds();
+
+  if (mWindowType == WindowType::Invisible) {
+    [mWindow setLevel:kCGDesktopWindowLevelKey];
+  }
+
+  if (mWindowType == WindowType::Popup) {
+    SetPopupWindowLevel();
+    [mWindow setBackgroundColor:[NSColor clearColor]];
+    [mWindow setOpaque:NO];
+
+    // When multiple spaces are in use and the browser is assigned to a
+    // particular space, override the "Assign To" space and display popups on
+    // the active space. Does not work with multiple displays. See
+    // NeedsRecreateToReshow() for multi-display with multi-space workaround.
+    if (!mAlwaysOnTop) {
+      NSWindowCollectionBehavior behavior = [mWindow collectionBehavior];
+      behavior |= NSWindowCollectionBehaviorMoveToActiveSpace;
+      [mWindow setCollectionBehavior:behavior];
+    }
+  } else {
+    // Non-popup windows are always opaque.
+    [mWindow setOpaque:YES];
+  }
+
+  NSWindowCollectionBehavior newBehavior = [mWindow collectionBehavior];
+  if (mAlwaysOnTop) {
+    [mWindow setLevel:NSFloatingWindowLevel];
+    newBehavior |= NSWindowCollectionBehaviorCanJoinAllSpaces;
+  }
+  [mWindow setCollectionBehavior:newBehavior];
+
+  [mWindow setContentMinSize:NSMakeSize(60, 60)];
+  [mWindow disableCursorRects];
+
+  // Make the window use CoreAnimation from the start, so that we don't
+  // switch from a non-CA window to a CA-window in the middle.
+  [[mWindow contentView] setWantsLayer:YES];
+
+  // Make sure the window starts out not draggable by the background.
+  // We will turn it on as necessary.
+  [mWindow setMovableByWindowBackground:NO];
+
+  [[WindowDataMap sharedWindowDataMap] ensureDataForWindow:mWindow];
+  mWindowMadeHere = true;
+
+  if (@available(macOS 10.14, *)) {
+    // Make the window respect the global appearance, which follows the browser.theme.toolbar-theme
+    // pref.
+    mWindow.appearanceSource = MOZGlobalAppearance.sharedInstance;
+  }
+
+  return NS_OK;
+
+  NS_OBJC_END_TRY_BLOCK_RETURN(NS_ERROR_FAILURE);
+}
+
+nsresult nsCocoaWindow::CreatePopupContentView(const LayoutDeviceIntRect& aRect,
+                                               widget::InitData* aInitData) {
+  NS_OBJC_BEGIN_TRY_BLOCK_RETURN;
+
+  // We need to make our content view a ChildView.
+  mPopupContentView = new nsChildView();
+  if (!mPopupContentView) return NS_ERROR_FAILURE;
+
+  NS_ADDREF(mPopupContentView);
+
+  nsIWidget* thisAsWidget = static_cast<nsIWidget*>(this);
+  nsresult rv = mPopupContentView->Create(thisAsWidget, nullptr, aRect, aInitData);
+  if (NS_WARN_IF(NS_FAILED(rv))) {
+    return rv;
+  }
+
+  NSView* contentView = [mWindow contentView];
+  ChildView* childView = (ChildView*)mPopupContentView->GetNativeData(NS_NATIVE_WIDGET);
+  [childView setFrame:[contentView bounds]];
+  [childView setAutoresizingMask:NSViewWidthSizable | NSViewHeightSizable];
+  [contentView addSubview:childView];
+
+  return NS_OK;
+
+  NS_OBJC_END_TRY_BLOCK_RETURN(NS_ERROR_FAILURE);
+}
+
+void nsCocoaWindow::Destroy() {
+  if (mOnDestroyCalled) return;
+  mOnDestroyCalled = true;
+
+  // SetFakeModal(true) is called for non-modal window opened by modal window.
+  // On Cocoa, it needs corresponding SetFakeModal(false) on destroy to restore
+  // ancestor windows' state.
+  if (mFakeModal) {
+    SetFakeModal(false);
+  }
+
+  // If we don't hide here we run into problems with panels, this is not ideal.
+  // (Bug 891424)
+  Show(false);
+
+  if (mPopupContentView) mPopupContentView->Destroy();
+
+  if (mFullscreenTransitionAnimation) {
+    [mFullscreenTransitionAnimation stopAnimation];
+    ReleaseFullscreenTransitionAnimation();
+  }
+
+  nsBaseWidget::Destroy();
+  // nsBaseWidget::Destroy() calls GetParent()->RemoveChild(this). But we
+  // don't implement GetParent(), so we need to do the equivalent here.
+  if (mParent) {
+    mParent->RemoveChild(this);
+  }
+  nsBaseWidget::OnDestroy();
+
+  if (mInFullScreenMode) {
+    // On Lion we don't have to mess with the OS chrome when in Full Screen
+    // mode.  But we do have to destroy the native window here (and not wait
+    // for that to happen in our destructor).  We don't switch away from the
+    // native window's space until the window is destroyed, and otherwise this
+    // might not happen for several seconds (because at least one object
+    // holding a reference to ourselves is usually waiting to be garbage-
+    // collected).  See bug 757618.
+    if (mInNativeFullScreenMode) {
+      DestroyNativeWindow();
+    } else if (mWindow) {
+      nsCocoaUtils::HideOSChromeOnScreen(false);
+    }
+  }
+}
+
+nsIWidget* nsCocoaWindow::GetSheetWindowParent(void) {
+  if (mWindowType != WindowType::Sheet) return nullptr;
+  nsCocoaWindow* parent = static_cast<nsCocoaWindow*>(mParent);
+  while (parent && (parent->mWindowType == WindowType::Sheet))
+    parent = static_cast<nsCocoaWindow*>(parent->mParent);
+  return parent;
+}
+
+void* nsCocoaWindow::GetNativeData(uint32_t aDataType) {
+  NS_OBJC_BEGIN_TRY_BLOCK_RETURN;
+
+  void* retVal = nullptr;
+
+  switch (aDataType) {
+    // to emulate how windows works, we always have to return a NSView
+    // for NS_NATIVE_WIDGET
+    case NS_NATIVE_WIDGET:
+      retVal = [mWindow contentView];
+      break;
+
+    case NS_NATIVE_WINDOW:
+      retVal = mWindow;
+      break;
+
+    case NS_NATIVE_GRAPHIC:
+      // There isn't anything that makes sense to return here,
+      // and it doesn't matter so just return nullptr.
+      NS_ERROR("Requesting NS_NATIVE_GRAPHIC on a top-level window!");
+      break;
+    case NS_RAW_NATIVE_IME_CONTEXT: {
+      retVal = GetPseudoIMEContext();
+      if (retVal) {
+        break;
+      }
+      NSView* view = mWindow ? [mWindow contentView] : nil;
+      if (view) {
+        retVal = [view inputContext];
+      }
+      // If inputContext isn't available on this window, return this window's
+      // pointer instead of nullptr since if this returns nullptr,
+      // IMEStateManager cannot manage composition with TextComposition
+      // instance.  Although, this case shouldn't occur.
+      if (NS_WARN_IF(!retVal)) {
+        retVal = this;
+      }
+      break;
+    }
+  }
+
+  return retVal;
+
+  NS_OBJC_END_TRY_BLOCK_RETURN(nullptr);
+}
+
+bool nsCocoaWindow::IsVisible() const {
+  NS_OBJC_BEGIN_TRY_BLOCK_RETURN;
+
+  return (mWindow && ([mWindow isVisibleOrBeingShown] || mSheetNeedsShow));
+
+  NS_OBJC_END_TRY_BLOCK_RETURN(false);
+}
+
+void nsCocoaWindow::SetModal(bool aState) {
+  NS_OBJC_BEGIN_TRY_IGNORE_BLOCK;
+
+  if (!mWindow) return;
+
+  // This is used during startup (outside the event loop) when creating
+  // the add-ons compatibility checking dialog and the profile manager UI;
+  // therefore, it needs to provide an autorelease pool to avoid cocoa
+  // objects leaking.
+  nsAutoreleasePool localPool;
+
+  mModal = aState;
+  nsCocoaWindow* ancestor = static_cast<nsCocoaWindow*>(mAncestorLink);
+  if (aState) {
+    ++gXULModalLevel;
+    // When a non-sheet window gets "set modal", make the window(s) that it
+    // appears over behave as they should.  We can't rely on native methods to
+    // do this, for the following reason:  The OS runs modal non-sheet windows
+    // in an event loop (using [NSApplication runModalForWindow:] or similar
+    // methods) that's incompatible with the modal event loop in AppWindow::
+    // ShowModal() (each of these event loops is "exclusive", and can't run at
+    // the same time as other (similar) event loops).
+    if (mWindowType != WindowType::Sheet) {
+      while (ancestor) {
+        if (ancestor->mNumModalDescendents++ == 0) {
+          NSWindow* aWindow = ancestor->GetCocoaWindow();
+          if (ancestor->mWindowType != WindowType::Invisible) {
+            [[aWindow standardWindowButton:NSWindowCloseButton] setEnabled:NO];
+            [[aWindow standardWindowButton:NSWindowMiniaturizeButton] setEnabled:NO];
+            [[aWindow standardWindowButton:NSWindowZoomButton] setEnabled:NO];
+          }
+        }
+        ancestor = static_cast<nsCocoaWindow*>(ancestor->mParent);
+      }
+      [mWindow setLevel:NSModalPanelWindowLevel];
+      nsCocoaWindowList* windowList = new nsCocoaWindowList;
+      if (windowList) {
+        windowList->window = this;  // Don't ADDREF
+        windowList->prev = gGeckoAppModalWindowList;
+        gGeckoAppModalWindowList = windowList;
+      }
+    }
+  } else {
+    --gXULModalLevel;
+    NS_ASSERTION(gXULModalLevel >= 0, "Mismatched call to nsCocoaWindow::SetModal(false)!");
+    if (mWindowType != WindowType::Sheet) {
+      while (ancestor) {
+        if (--ancestor->mNumModalDescendents == 0) {
+          NSWindow* aWindow = ancestor->GetCocoaWindow();
+          if (ancestor->mWindowType != WindowType::Invisible) {
+            [[aWindow standardWindowButton:NSWindowCloseButton] setEnabled:YES];
+            [[aWindow standardWindowButton:NSWindowMiniaturizeButton] setEnabled:YES];
+            [[aWindow standardWindowButton:NSWindowZoomButton] setEnabled:YES];
+          }
+        }
+        NS_ASSERTION(ancestor->mNumModalDescendents >= 0, "Widget hierarchy changed while modal!");
+        ancestor = static_cast<nsCocoaWindow*>(ancestor->mParent);
+      }
+      if (gGeckoAppModalWindowList) {
+        NS_ASSERTION(gGeckoAppModalWindowList->window == this,
+                     "Widget hierarchy changed while modal!");
+        nsCocoaWindowList* saved = gGeckoAppModalWindowList;
+        gGeckoAppModalWindowList = gGeckoAppModalWindowList->prev;
+        delete saved;  // "window" not ADDREFed
+      }
+      if (mWindowType == WindowType::Popup)
+        SetPopupWindowLevel();
+      else
+        [mWindow setLevel:NSNormalWindowLevel];
+    }
+  }
+
+  NS_OBJC_END_TRY_IGNORE_BLOCK;
+}
+
+void nsCocoaWindow::SetFakeModal(bool aState) {
+  mFakeModal = aState;
+  SetModal(aState);
+}
+
+bool nsCocoaWindow::IsRunningAppModal() { return [NSApp _isRunningAppModal]; }
+
+// Hide or show this window
+void nsCocoaWindow::Show(bool bState) {
+  NS_OBJC_BEGIN_TRY_IGNORE_BLOCK;
+
+  if (!mWindow) return;
+
+  if (!mSheetNeedsShow) {
+    // Early exit if our current visibility state is already the requested state.
+    if (bState == ([mWindow isVisible] || [mWindow isBeingShown])) {
+      return;
+    }
+  }
+
+  [mWindow setBeingShown:bState];
+  if (bState && !mWasShown) {
+    mWasShown = true;
+  }
+
+  nsIWidget* parentWidget = mParent;
+  nsCOMPtr<nsPIWidgetCocoa> piParentWidget(do_QueryInterface(parentWidget));
+  NSWindow* nativeParentWindow =
+      (parentWidget) ? (NSWindow*)parentWidget->GetNativeData(NS_NATIVE_WINDOW) : nil;
+
+  if (bState && !mBounds.IsEmpty()) {
+    // If we had set the activationPolicy to accessory, then right now we won't
+    // have a dock icon. Make sure that we undo that and show a dock icon now that
+    // we're going to show a window.
+    if ([NSApp activationPolicy] != NSApplicationActivationPolicyRegular) {
+      [NSApp setActivationPolicy:NSApplicationActivationPolicyRegular];
+      PR_SetEnv("MOZ_APP_NO_DOCK=");
+    }
+
+    // Don't try to show a popup when the parent isn't visible or is minimized.
+    if (mWindowType == WindowType::Popup && nativeParentWindow) {
+      if (![nativeParentWindow isVisible] || [nativeParentWindow isMiniaturized]) {
+        return;
+      }
+    }
+
+    if (mPopupContentView) {
+      // Ensure our content view is visible. We never need to hide it.
+      mPopupContentView->Show(true);
+    }
+
+    if (mWindowType == WindowType::Sheet) {
+      // bail if no parent window (its basically what we do in Carbon)
+      if (!nativeParentWindow || !piParentWidget) return;
+
+      NSWindow* topNonSheetWindow = nativeParentWindow;
+
+      // If this sheet is the child of another sheet, hide the parent so that
+      // this sheet can be displayed. Leave the parent mSheetNeedsShow alone,
+      // that is only used to handle sibling sheet contention. The parent will
+      // return once there are no more child sheets.
+      bool parentIsSheet = false;
+      if (NS_SUCCEEDED(piParentWidget->GetIsSheet(&parentIsSheet)) && parentIsSheet) {
+        piParentWidget->GetSheetWindowParent(&topNonSheetWindow);
+#ifdef MOZ_THUNDERBIRD
+        [NSApp endSheet:nativeParentWindow];
+#else
+        [nativeParentWindow.sheetParent endSheet:nativeParentWindow];
+#endif
+      }
+
+      nsCOMPtr<nsIWidget> sheetShown;
+      if (NS_SUCCEEDED(piParentWidget->GetChildSheet(true, getter_AddRefs(sheetShown))) &&
+          (!sheetShown || sheetShown == this)) {
+        // If this sheet is already the sheet actually being shown, don't
+        // tell it to show again. Otherwise the number of calls to
+#ifdef MOZ_THUNDERBIRD
+        // [NSApp beginSheet...] won't match up with [NSApp endSheet...].
+#else
+        // [NSWindow beginSheet...] won't match up with [NSWindow endSheet...].
+#endif
+        if (![mWindow isVisible]) {
+          mSheetNeedsShow = false;
+          mSheetWindowParent = topNonSheetWindow;
+#ifdef MOZ_THUNDERBIRD
+          // Only set contextInfo if our parent isn't a sheet.
+          NSWindow* contextInfo = parentIsSheet ? nil : mSheetWindowParent;
+          [TopLevelWindowData deactivateInWindow:mSheetWindowParent];
+          [NSApp beginSheet:mWindow
+              modalForWindow:mSheetWindowParent
+               modalDelegate:mDelegate
+              didEndSelector:@selector(didEndSheet:returnCode:contextInfo:)
+                 contextInfo:contextInfo];
+#else
+          NSWindow* sheet = mWindow;
+          NSWindow* nonSheetParent = parentIsSheet ? nil : mSheetWindowParent;
+          [TopLevelWindowData deactivateInWindow:mSheetWindowParent];
+          [mSheetWindowParent beginSheet:sheet
+                       completionHandler:^(NSModalResponse returnCode) {
+                         // Note: 'nonSheetParent' (if it is set) is the window that is the parent
+                         // of the sheet. If it's set, 'nonSheetParent' is always the top- level
+                         // window, not another sheet itself.  But 'nonSheetParent' is nil if our
+                         // parent window is also a sheet -- in that case we shouldn't send the
+                         // top-level window any activate events (because it's our parent window
+                         // that needs to get these events, not the top-level window).
+                         [TopLevelWindowData deactivateInWindow:sheet];
+                         [sheet orderOut:nil];
+                         if (nonSheetParent) {
+                           [TopLevelWindowData activateInWindow:nonSheetParent];
+                         }
+                       }];
+#endif
+          [TopLevelWindowData activateInWindow:mWindow];
+          SendSetZLevelEvent();
+        }
+      } else {
+        // A sibling of this sheet is active, don't show this sheet yet.
+        // When the active sheet hides, its brothers and sisters that have
+        // mSheetNeedsShow set will have their opportunities to display.
+        mSheetNeedsShow = true;
+      }
+    } else if (mWindowType == WindowType::Popup) {
+      // For reasons that aren't yet clear, calls to [NSWindow orderFront:] or
+      // [NSWindow makeKeyAndOrderFront:] can sometimes trigger "Error (1000)
+      // creating CGSWindow", which in turn triggers an internal inconsistency
+      // NSException.  These errors shouldn't be fatal.  So we need to wrap
+      // calls to ...orderFront: in TRY blocks.  See bmo bug 470864.
+      NS_OBJC_BEGIN_TRY_IGNORE_BLOCK;
+      [[mWindow contentView] setNeedsDisplay:YES];
+      [mWindow orderFront:nil];
+      NS_OBJC_END_TRY_IGNORE_BLOCK;
+      SendSetZLevelEvent();
+      // If our popup window is a non-native context menu, tell the OS (and
+      // other programs) that a menu has opened.  This is how the OS knows to
+      // close other programs' context menus when ours open.
+      if ([mWindow isKindOfClass:[PopupWindow class]] && [(PopupWindow*)mWindow isContextMenu]) {
+        [[NSDistributedNotificationCenter defaultCenter]
+            postNotificationName:@"com.apple.HIToolbox.beginMenuTrackingNotification"
+                          object:@"org.mozilla.gecko.PopupWindow"];
+      }
+
+      // If a parent window was supplied and this is a popup at the parent
+      // level, set its child window. This will cause the child window to
+      // appear above the parent and move when the parent does. Setting this
+      // needs to happen after the _setWindowNumber calls above, otherwise the
+      // window doesn't focus properly.
+      if (nativeParentWindow && mPopupLevel == PopupLevel::Parent)
+        [nativeParentWindow addChildWindow:mWindow ordered:NSWindowAbove];
+    } else {
+      NS_OBJC_BEGIN_TRY_IGNORE_BLOCK;
+      if (mWindowType == WindowType::TopLevel &&
+          [mWindow respondsToSelector:@selector(setAnimationBehavior:)]) {
+        NSWindowAnimationBehavior behavior;
+        if (mIsAnimationSuppressed) {
+          behavior = NSWindowAnimationBehaviorNone;
+        } else {
+          switch (mAnimationType) {
+            case nsIWidget::eDocumentWindowAnimation:
+              behavior = NSWindowAnimationBehaviorDocumentWindow;
+              break;
+            default:
+              MOZ_FALLTHROUGH_ASSERT("unexpected mAnimationType value");
+            case nsIWidget::eGenericWindowAnimation:
+              behavior = NSWindowAnimationBehaviorDefault;
+              break;
+          }
+        }
+        [mWindow setAnimationBehavior:behavior];
+        mWindowAnimationBehavior = behavior;
+      }
+
+      // We don't want alwaysontop windows to pull focus when they're opened,
+      // as these tend to be for peripheral indicators and displays.
+      if (mAlwaysOnTop) {
+        [mWindow orderFront:nil];
+      } else {
+        [mWindow makeKeyAndOrderFront:nil];
+      }
+      NS_OBJC_END_TRY_IGNORE_BLOCK;
+      SendSetZLevelEvent();
+    }
+  } else {
+    // roll up any popups if a top-level window is going away
+    if (mWindowType == WindowType::TopLevel || mWindowType == WindowType::Dialog) {
+      RollUpPopups();
+    }
+
+    // now get rid of the window/sheet
+    if (mWindowType == WindowType::Sheet) {
+      if (mSheetNeedsShow) {
+        // This is an attempt to hide a sheet that never had a chance to
+        // be shown. There's nothing to do other than make sure that it
+        // won't show.
+        mSheetNeedsShow = false;
+      } else {
+        // get sheet's parent *before* hiding the sheet (which breaks the linkage)
+        NSWindow* sheetParent = mSheetWindowParent;
+
+        // hide the sheet
+#ifdef MOZ_THUNDERBIRD
+        [NSApp endSheet:mWindow];
+#else
+        [mSheetWindowParent endSheet:mWindow];
+#endif
+        [TopLevelWindowData deactivateInWindow:mWindow];
+
+        nsCOMPtr<nsIWidget> siblingSheetToShow;
+        bool parentIsSheet = false;
+
+        if (nativeParentWindow && piParentWidget &&
+            NS_SUCCEEDED(
+                piParentWidget->GetChildSheet(false, getter_AddRefs(siblingSheetToShow))) &&
+            siblingSheetToShow) {
+          // First, give sibling sheets an opportunity to show.
+          siblingSheetToShow->Show(true);
+        } else if (nativeParentWindow && piParentWidget &&
+                   NS_SUCCEEDED(piParentWidget->GetIsSheet(&parentIsSheet)) && parentIsSheet) {
+#ifdef MOZ_THUNDERBIRD
+          // Only set contextInfo if the parent of the parent sheet we're about
+          // to restore isn't itself a sheet.
+          NSWindow* contextInfo = sheetParent;
+#else
+          // Only set nonSheetGrandparent if the parent of the parent sheet we're about
+          // to restore isn't itself a sheet.
+          NSWindow* nonSheetGrandparent = sheetParent;
+#endif
+          nsIWidget* grandparentWidget = nil;
+          if (NS_SUCCEEDED(piParentWidget->GetRealParent(&grandparentWidget)) &&
+              grandparentWidget) {
+            nsCOMPtr<nsPIWidgetCocoa> piGrandparentWidget(do_QueryInterface(grandparentWidget));
+            bool grandparentIsSheet = false;
+            if (piGrandparentWidget &&
+                NS_SUCCEEDED(piGrandparentWidget->GetIsSheet(&grandparentIsSheet)) &&
+                grandparentIsSheet) {
+#ifdef MOZ_THUNDERBIRD
+              contextInfo = nil;
+#else
+              nonSheetGrandparent = nil;
+#endif
+            }
+          }
+          // If there are no sibling sheets, but the parent is a sheet, restore
+          // it.  It wasn't sent any deactivate events when it was hidden, so
+          // don't call through Show, just let the OS put it back up.
+#ifdef MOZ_THUNDERBIRD
+          [NSApp beginSheet:nativeParentWindow
+              modalForWindow:sheetParent
+               modalDelegate:[nativeParentWindow delegate]
+              didEndSelector:@selector(didEndSheet:returnCode:contextInfo:)
+                 contextInfo:contextInfo];
+#else
+          [nativeParentWindow beginSheet:sheetParent
+                       completionHandler:^(NSModalResponse returnCode) {
+                         // Note: 'nonSheetGrandparent' (if it is set) is the window that is the
+                         // parent of sheetParent. If it's set, 'nonSheetGrandparent' is always the
+                         // top-level window, not another sheet itself.  But 'nonSheetGrandparent'
+                         // is nil if our parent window is also a sheet -- in that case we shouldn't
+                         // send the top-level window any activate events (because it's our parent
+                         // window that needs to get these events, not the top-level window).
+                         [TopLevelWindowData deactivateInWindow:sheetParent];
+                         [sheetParent orderOut:nil];
+                         if (nonSheetGrandparent) {
+                           [TopLevelWindowData activateInWindow:nonSheetGrandparent];
+                         }
+                       }];
+#endif
+        } else {
+          // Sheet, that was hard.  No more siblings or parents, going back
+          // to a real window.
+          NS_OBJC_BEGIN_TRY_IGNORE_BLOCK;
+          [sheetParent makeKeyAndOrderFront:nil];
+          NS_OBJC_END_TRY_IGNORE_BLOCK;
+        }
+        SendSetZLevelEvent();
+      }
+    } else {
+      // If the window is a popup window with a parent window we need to
+      // unhook it here before ordering it out. When you order out the child
+      // of a window it hides the parent window.
+      if (mWindowType == WindowType::Popup && nativeParentWindow)
+        [nativeParentWindow removeChildWindow:mWindow];
+
+      [mWindow orderOut:nil];
+
+      // If our popup window is a non-native context menu, tell the OS (and
+      // other programs) that a menu has closed.
+      if ([mWindow isKindOfClass:[PopupWindow class]] && [(PopupWindow*)mWindow isContextMenu]) {
+        [[NSDistributedNotificationCenter defaultCenter]
+            postNotificationName:@"com.apple.HIToolbox.endMenuTrackingNotification"
+                          object:@"org.mozilla.gecko.PopupWindow"];
+      }
+    }
+  }
+
+  [mWindow setBeingShown:NO];
+
+  NS_OBJC_END_TRY_IGNORE_BLOCK;
+}
+
+// Work around a problem where with multiple displays and multiple spaces
+// enabled, where the browser is assigned to a single display or space, popup
+// windows that are reshown after being hidden with [NSWindow orderOut] show on
+// the assigned space even when opened from another display. Apply the
+// workaround whenever more than one display is enabled.
+bool nsCocoaWindow::NeedsRecreateToReshow() {
+  // Limit the workaround to popup windows because only they need to override
+  // the "Assign To" setting. i.e., to display where the parent window is.
+  return (mWindowType == WindowType::Popup) && mWasShown && ([[NSScreen screens] count] > 1);
+}
+
+WindowRenderer* nsCocoaWindow::GetWindowRenderer() {
+  if (mPopupContentView) {
+    return mPopupContentView->GetWindowRenderer();
+  }
+  return nullptr;
+}
+
+TransparencyMode nsCocoaWindow::GetTransparencyMode() {
+  NS_OBJC_BEGIN_TRY_BLOCK_RETURN;
+
+  return (!mWindow || [mWindow isOpaque]) ? TransparencyMode::Opaque
+                                          : TransparencyMode::Transparent;
+
+  NS_OBJC_END_TRY_BLOCK_RETURN(TransparencyMode::Opaque);
+}
+
+// This is called from nsMenuPopupFrame when making a popup transparent.
+void nsCocoaWindow::SetTransparencyMode(TransparencyMode aMode) {
+  NS_OBJC_BEGIN_TRY_IGNORE_BLOCK;
+
+  // Only respect calls for popup windows.
+  if (!mWindow || mWindowType != WindowType::Popup) {
+    return;
+  }
+
+  BOOL isTransparent = aMode == TransparencyMode::Transparent;
+  BOOL currentTransparency = ![mWindow isOpaque];
+  if (isTransparent != currentTransparency) {
+    [mWindow setOpaque:!isTransparent];
+    [mWindow setBackgroundColor:(isTransparent ? [NSColor clearColor] : [NSColor whiteColor])];
+  }
+
+  NS_OBJC_END_TRY_IGNORE_BLOCK;
+}
+
+void nsCocoaWindow::Enable(bool aState) {}
+
+bool nsCocoaWindow::IsEnabled() const { return true; }
+
+void nsCocoaWindow::ConstrainPosition(DesktopIntPoint& aPoint) {
+  NS_OBJC_BEGIN_TRY_IGNORE_BLOCK;
+
+  if (!mWindow || ![mWindow screen]) {
+    return;
+  }
+
+  nsIntRect screenBounds;
+
+  int32_t width, height;
+
+  NSRect frame = [mWindow frame];
+
+  // zero size rects confuse the screen manager
+  width = std::max<int32_t>(frame.size.width, 1);
+  height = std::max<int32_t>(frame.size.height, 1);
+
+  nsCOMPtr<nsIScreenManager> screenMgr = do_GetService("@mozilla.org/gfx/screenmanager;1");
+  if (screenMgr) {
+    nsCOMPtr<nsIScreen> screen;
+    screenMgr->ScreenForRect(aPoint.x, aPoint.y, width, height, getter_AddRefs(screen));
+
+    if (screen) {
+      screen->GetRectDisplayPix(&(screenBounds.x), &(screenBounds.y), &(screenBounds.width),
+                                &(screenBounds.height));
+    }
+  }
+
+  if (aPoint.x < screenBounds.x) {
+    aPoint.x = screenBounds.x;
+  } else if (aPoint.x >= screenBounds.x + screenBounds.width - width) {
+    aPoint.x = screenBounds.x + screenBounds.width - width;
+  }
+
+  if (aPoint.y < screenBounds.y) {
+    aPoint.y = screenBounds.y;
+  } else if (aPoint.y >= screenBounds.y + screenBounds.height - height) {
+    aPoint.y = screenBounds.y + screenBounds.height - height;
+  }
+
+  NS_OBJC_END_TRY_IGNORE_BLOCK;
+}
+
+void nsCocoaWindow::SetSizeConstraints(const SizeConstraints& aConstraints) {
+  NS_OBJC_BEGIN_TRY_IGNORE_BLOCK;
+
+  // Popups can be smaller than (32, 32)
+  NSRect rect = (mWindowType == WindowType::Popup) ? NSZeroRect : NSMakeRect(0.0, 0.0, 32, 32);
+  rect = [mWindow frameRectForChildViewRect:rect];
+
+  SizeConstraints c = aConstraints;
+
+  if (c.mScale.scale == MOZ_WIDGET_INVALID_SCALE) {
+    c.mScale.scale = BackingScaleFactor();
+  }
+
+  c.mMinSize.width = std::max(nsCocoaUtils::CocoaPointsToDevPixels(rect.size.width, c.mScale.scale),
+                              c.mMinSize.width);
+  c.mMinSize.height = std::max(
+      nsCocoaUtils::CocoaPointsToDevPixels(rect.size.height, c.mScale.scale), c.mMinSize.height);
+
+  NSSize minSize = {nsCocoaUtils::DevPixelsToCocoaPoints(c.mMinSize.width, c.mScale.scale),
+                    nsCocoaUtils::DevPixelsToCocoaPoints(c.mMinSize.height, c.mScale.scale)};
+  [mWindow setMinSize:minSize];
+
+  c.mMaxSize.width = std::max(
+      nsCocoaUtils::CocoaPointsToDevPixels(c.mMaxSize.width, c.mScale.scale), c.mMaxSize.width);
+  c.mMaxSize.height = std::max(
+      nsCocoaUtils::CocoaPointsToDevPixels(c.mMaxSize.height, c.mScale.scale), c.mMaxSize.height);
+
+  NSSize maxSize = {c.mMaxSize.width == NS_MAXSIZE
+                        ? FLT_MAX
+                        : nsCocoaUtils::DevPixelsToCocoaPoints(c.mMaxSize.width, c.mScale.scale),
+                    c.mMaxSize.height == NS_MAXSIZE
+                        ? FLT_MAX
+                        : nsCocoaUtils::DevPixelsToCocoaPoints(c.mMaxSize.height, c.mScale.scale)};
+  [mWindow setMaxSize:maxSize];
+
+  nsBaseWidget::SetSizeConstraints(c);
+
+  NS_OBJC_END_TRY_IGNORE_BLOCK;
+}
+
+// Coordinates are desktop pixels
+void nsCocoaWindow::Move(double aX, double aY) {
+  NS_OBJC_BEGIN_TRY_IGNORE_BLOCK;
+
+  if (!mWindow) {
+    return;
+  }
+
+  // The point we have is in Gecko coordinates (origin top-left). Convert
+  // it to Cocoa ones (origin bottom-left).
+  NSPoint coord = {static_cast<float>(aX),
+                   static_cast<float>(nsCocoaUtils::FlippedScreenY(NSToIntRound(aY)))};
+
+  NSRect frame = [mWindow frame];
+  if (frame.origin.x != coord.x || frame.origin.y + frame.size.height != coord.y) {
+    [mWindow setFrameTopLeftPoint:coord];
+  }
+
+  NS_OBJC_END_TRY_IGNORE_BLOCK;
+}
+
+void nsCocoaWindow::SetSizeMode(nsSizeMode aMode) {
+  if (aMode == nsSizeMode_Normal) {
+    QueueTransition(TransitionType::Windowed);
+  } else if (aMode == nsSizeMode_Minimized) {
+    QueueTransition(TransitionType::Miniaturize);
+  } else if (aMode == nsSizeMode_Maximized) {
+    QueueTransition(TransitionType::Zoom);
+  } else if (aMode == nsSizeMode_Fullscreen) {
+    MakeFullScreen(true);
+  }
+}
+
+// The (work)space switching implementation below was inspired by Phoenix:
+// https://github.com/kasper/phoenix/tree/d6c877f62b30a060dff119d8416b0934f76af534
+// License: MIT.
+
+// Runtime `CGSGetActiveSpace` library function feature detection.
+typedef CGSSpaceID (*CGSGetActiveSpaceFunc)(CGSConnection cid);
+static CGSGetActiveSpaceFunc GetCGSGetActiveSpaceFunc() {
+  static CGSGetActiveSpaceFunc func = nullptr;
+  static bool lookedUpFunc = false;
+  if (!lookedUpFunc) {
+    func = (CGSGetActiveSpaceFunc)dlsym(RTLD_DEFAULT, "CGSGetActiveSpace");
+    lookedUpFunc = true;
+  }
+  return func;
+}
+// Runtime `CGSCopyManagedDisplaySpaces` library function feature detection.
+typedef CFArrayRef (*CGSCopyManagedDisplaySpacesFunc)(CGSConnection cid);
+static CGSCopyManagedDisplaySpacesFunc GetCGSCopyManagedDisplaySpacesFunc() {
+  static CGSCopyManagedDisplaySpacesFunc func = nullptr;
+  static bool lookedUpFunc = false;
+  if (!lookedUpFunc) {
+    func = (CGSCopyManagedDisplaySpacesFunc)dlsym(RTLD_DEFAULT, "CGSCopyManagedDisplaySpaces");
+    lookedUpFunc = true;
+  }
+  return func;
+}
+// Runtime `CGSCopySpacesForWindows` library function feature detection.
+typedef CFArrayRef (*CGSCopySpacesForWindowsFunc)(CGSConnection cid, CGSSpaceMask mask,
+                                                  CFArrayRef windowIDs);
+static CGSCopySpacesForWindowsFunc GetCGSCopySpacesForWindowsFunc() {
+  static CGSCopySpacesForWindowsFunc func = nullptr;
+  static bool lookedUpFunc = false;
+  if (!lookedUpFunc) {
+    func = (CGSCopySpacesForWindowsFunc)dlsym(RTLD_DEFAULT, "CGSCopySpacesForWindows");
+    lookedUpFunc = true;
+  }
+  return func;
+}
+// Runtime `CGSAddWindowsToSpaces` library function feature detection.
+typedef void (*CGSAddWindowsToSpacesFunc)(CGSConnection cid, CFArrayRef windowIDs,
+                                          CFArrayRef spaceIDs);
+static CGSAddWindowsToSpacesFunc GetCGSAddWindowsToSpacesFunc() {
+  static CGSAddWindowsToSpacesFunc func = nullptr;
+  static bool lookedUpFunc = false;
+  if (!lookedUpFunc) {
+    func = (CGSAddWindowsToSpacesFunc)dlsym(RTLD_DEFAULT, "CGSAddWindowsToSpaces");
+    lookedUpFunc = true;
+  }
+  return func;
+}
+// Runtime `CGSRemoveWindowsFromSpaces` library function feature detection.
+typedef void (*CGSRemoveWindowsFromSpacesFunc)(CGSConnection cid, CFArrayRef windowIDs,
+                                               CFArrayRef spaceIDs);
+static CGSRemoveWindowsFromSpacesFunc GetCGSRemoveWindowsFromSpacesFunc() {
+  static CGSRemoveWindowsFromSpacesFunc func = nullptr;
+  static bool lookedUpFunc = false;
+  if (!lookedUpFunc) {
+    func = (CGSRemoveWindowsFromSpacesFunc)dlsym(RTLD_DEFAULT, "CGSRemoveWindowsFromSpaces");
+    lookedUpFunc = true;
+  }
+  return func;
+}
+
+void nsCocoaWindow::GetWorkspaceID(nsAString& workspaceID) {
+  workspaceID.Truncate();
+  int32_t sid = GetWorkspaceID();
+  if (sid != 0) {
+    workspaceID.AppendInt(sid);
+  }
+}
+
+int32_t nsCocoaWindow::GetWorkspaceID() {
+  NS_OBJC_BEGIN_TRY_IGNORE_BLOCK;
+
+  // Mac OSX space IDs start at '1' (default space), so '0' means 'unknown',
+  // effectively.
+  CGSSpaceID sid = 0;
+
+  CGSCopySpacesForWindowsFunc CopySpacesForWindows = GetCGSCopySpacesForWindowsFunc();
+  if (!CopySpacesForWindows) {
+    return sid;
+  }
+
+  CGSConnection cid = _CGSDefaultConnection();
+  // Fetch all spaces that this window belongs to (in order).
+  NSArray<NSNumber*>* spaceIDs = CFBridgingRelease(CopySpacesForWindows(
+      cid, kCGSAllSpacesMask, (__bridge CFArrayRef) @[ @([mWindow windowNumber]) ]));
+  if ([spaceIDs count]) {
+    // When spaces are found, return the first one.
+    // We don't support a single window painted across multiple places for now.
+    sid = [spaceIDs[0] integerValue];
+  } else {
+    // Fall back to the workspace that's currently active, which is '1' in the
+    // common case.
+    CGSGetActiveSpaceFunc GetActiveSpace = GetCGSGetActiveSpaceFunc();
+    if (GetActiveSpace) {
+      sid = GetActiveSpace(cid);
+    }
+  }
+
+  return sid;
+
+  NS_OBJC_END_TRY_IGNORE_BLOCK;
+}
+
+void nsCocoaWindow::MoveToWorkspace(const nsAString& workspaceIDStr) {
+  NS_OBJC_BEGIN_TRY_IGNORE_BLOCK;
+
+  if ([NSScreen screensHaveSeparateSpaces] && [[NSScreen screens] count] > 1) {
+    // We don't support moving to a workspace when the user has this option
+    // enabled in Mission Control.
+    return;
+  }
+
+  nsresult rv = NS_OK;
+  int32_t workspaceID = workspaceIDStr.ToInteger(&rv);
+  if (NS_FAILED(rv)) {
+    return;
+  }
+
+  CGSConnection cid = _CGSDefaultConnection();
+  int32_t currentSpace = GetWorkspaceID();
+  // If an empty workspace ID is passed in (not valid on OSX), or when the
+  // window is already on this workspace, we don't need to do anything.
+  if (!workspaceID || workspaceID == currentSpace) {
+    return;
+  }
+
+  CGSCopyManagedDisplaySpacesFunc CopyManagedDisplaySpaces = GetCGSCopyManagedDisplaySpacesFunc();
+  CGSAddWindowsToSpacesFunc AddWindowsToSpaces = GetCGSAddWindowsToSpacesFunc();
+  CGSRemoveWindowsFromSpacesFunc RemoveWindowsFromSpaces = GetCGSRemoveWindowsFromSpacesFunc();
+  if (!CopyManagedDisplaySpaces || !AddWindowsToSpaces || !RemoveWindowsFromSpaces) {
+    return;
+  }
+
+  // Fetch an ordered list of all known spaces.
+  NSArray* displaySpacesInfo = CFBridgingRelease(CopyManagedDisplaySpaces(cid));
+  // When we found the space we're looking for, we can bail out of the loop
+  // early, which this local variable is used for.
+  BOOL found = false;
+  for (NSDictionary<NSString*, id>* spacesInfo in displaySpacesInfo) {
+    NSArray<NSNumber*>* sids = [spacesInfo[CGSSpacesKey] valueForKey:CGSSpaceIDKey];
+    for (NSNumber* sid in sids) {
+      // If we found our space in the list, we're good to go and can jump out of
+      // this loop.
+      if ((int)[sid integerValue] == workspaceID) {
+        found = true;
+        break;
+      }
+    }
+    if (found) {
+      break;
+    }
+  }
+
+  // We were unable to find the space to correspond with the workspaceID as
+  // requested, so let's bail out.
+  if (!found) {
+    return;
+  }
+
+  // First we add the window to the appropriate space.
+  AddWindowsToSpaces(cid, (__bridge CFArrayRef) @[ @([mWindow windowNumber]) ],
+                     (__bridge CFArrayRef) @[ @(workspaceID) ]);
+  // Then we remove the window from the active space.
+  RemoveWindowsFromSpaces(cid, (__bridge CFArrayRef) @[ @([mWindow windowNumber]) ],
+                          (__bridge CFArrayRef) @[ @(currentSpace) ]);
+
+  NS_OBJC_END_TRY_IGNORE_BLOCK;
+}
+
+void nsCocoaWindow::SuppressAnimation(bool aSuppress) {
+  if ([mWindow respondsToSelector:@selector(setAnimationBehavior:)]) {
+    if (aSuppress) {
+      [mWindow setIsAnimationSuppressed:YES];
+      [mWindow setAnimationBehavior:NSWindowAnimationBehaviorNone];
+    } else {
+      [mWindow setIsAnimationSuppressed:NO];
+      [mWindow setAnimationBehavior:mWindowAnimationBehavior];
+    }
+  }
+}
+
+// This has to preserve the window's frame bounds.
+// This method requires (as does the Windows impl.) that you call Resize shortly
+// after calling HideWindowChrome. See bug 498835 for fixing this.
+void nsCocoaWindow::HideWindowChrome(bool aShouldHide) {
+  NS_OBJC_BEGIN_TRY_IGNORE_BLOCK;
+
+  if (!mWindow || !mWindowMadeHere ||
+      (mWindowType != WindowType::TopLevel && mWindowType != WindowType::Dialog))
+    return;
+
+  BOOL isVisible = [mWindow isVisible];
+
+  // Remove child windows.
+  NSArray* childWindows = [mWindow childWindows];
+  NSEnumerator* enumerator = [childWindows objectEnumerator];
+  NSWindow* child = nil;
+  while ((child = [enumerator nextObject])) {
+    [mWindow removeChildWindow:child];
+  }
+
+  // Remove the views in the old window's content view.
+  // The NSArray is autoreleased and retains its NSViews.
+  NSArray<NSView*>* contentViewContents = [mWindow contentViewContents];
+  for (NSView* view in contentViewContents) {
+    [view removeFromSuperviewWithoutNeedingDisplay];
+  }
+
+  // Save state (like window title).
+  NSMutableDictionary* state = [mWindow exportState];
+
+  // Recreate the window with the right border style.
+  NSRect frameRect = [mWindow frame];
+  DestroyNativeWindow();
+  nsresult rv = CreateNativeWindow(frameRect, aShouldHide ? BorderStyle::None : mBorderStyle, true,
+                                   mWindow.restorable);
+  NS_ENSURE_SUCCESS_VOID(rv);
+
+  // Re-import state.
+  [mWindow importState:state];
+
+  // Add the old content view subviews to the new window's content view.
+  for (NSView* view in contentViewContents) {
+    [[mWindow contentView] addSubview:view];
+  }
+
+  // Reparent child windows.
+  enumerator = [childWindows objectEnumerator];
+  while ((child = [enumerator nextObject])) {
+    [mWindow addChildWindow:child ordered:NSWindowAbove];
+  }
+
+  // Show the new window.
+  if (isVisible) {
+    bool wasAnimationSuppressed = mIsAnimationSuppressed;
+    mIsAnimationSuppressed = true;
+    Show(true);
+    mIsAnimationSuppressed = wasAnimationSuppressed;
+  }
+
+  NS_OBJC_END_TRY_IGNORE_BLOCK;
+}
+
+class FullscreenTransitionData : public nsISupports {
+ public:
+  NS_DECL_ISUPPORTS
+
+  explicit FullscreenTransitionData(NSWindow* aWindow) : mTransitionWindow(aWindow) {}
+
+  NSWindow* mTransitionWindow;
+
+ private:
+  virtual ~FullscreenTransitionData() { [mTransitionWindow close]; }
+};
+
+NS_IMPL_ISUPPORTS0(FullscreenTransitionData)
+
+@interface FullscreenTransitionDelegate : NSObject <NSAnimationDelegate> {
+ @public
+  nsCocoaWindow* mWindow;
+  nsIRunnable* mCallback;
+}
+@end
+
+@implementation FullscreenTransitionDelegate
+- (void)cleanupAndDispatch:(NSAnimation*)animation {
+  [animation setDelegate:nil];
+  [self autorelease];
+  // The caller should have added ref for us.
+  NS_DispatchToMainThread(already_AddRefed<nsIRunnable>(mCallback));
+}
+
+- (void)animationDidEnd:(NSAnimation*)animation {
+  MOZ_ASSERT(animation == mWindow->FullscreenTransitionAnimation(),
+             "Should be handling the only animation on the window");
+  mWindow->ReleaseFullscreenTransitionAnimation();
+  [self cleanupAndDispatch:animation];
+}
+
+- (void)animationDidStop:(NSAnimation*)animation {
+  [self cleanupAndDispatch:animation];
+}
+@end
+
+static bool AlwaysUsesNativeFullScreen() {
+  return Preferences::GetBool("full-screen-api.macos-native-full-screen", false);
+}
+
+/* virtual */ bool nsCocoaWindow::PrepareForFullscreenTransition(nsISupports** aData) {
+  if (AlwaysUsesNativeFullScreen()) {
+    return false;
+  }
+
+  // Our fullscreen transition creates a new window occluding this window.
+  // That triggers an occlusion event which can cause DOM fullscreen requests
+  // to fail due to the context not being focused at the time the focus check
+  // is performed in the child process. Until the transition is cleaned up in
+  // CleanupFullscreenTransition(), ignore occlusion events for this window.
+  // If this method is changed to return false, the transition will not be
+  // performed and mIgnoreOcclusionCount should not be incremented.
+  MOZ_ASSERT(mIgnoreOcclusionCount >= 0);
+  mIgnoreOcclusionCount++;
+
+  nsCOMPtr<nsIScreen> widgetScreen = GetWidgetScreen();
+  NSScreen* cocoaScreen = ScreenHelperCocoa::CocoaScreenForScreen(widgetScreen);
+
+  NSWindow* win = [[NSWindow alloc] initWithContentRect:[cocoaScreen frame]
+                                              styleMask:NSWindowStyleMaskBorderless
+                                                backing:NSBackingStoreBuffered
+                                                  defer:YES];
+  [win setBackgroundColor:[NSColor blackColor]];
+  [win setAlphaValue:0];
+  [win setIgnoresMouseEvents:YES];
+  [win setLevel:NSScreenSaverWindowLevel];
+  [win makeKeyAndOrderFront:nil];
+
+  auto data = new FullscreenTransitionData(win);
+  *aData = data;
+  NS_ADDREF(data);
+  return true;
+}
+
+/* virtual */ void nsCocoaWindow::CleanupFullscreenTransition() {
+  MOZ_ASSERT(mIgnoreOcclusionCount > 0);
+  mIgnoreOcclusionCount--;
+}
+
+/* virtual */ void nsCocoaWindow::PerformFullscreenTransition(FullscreenTransitionStage aStage,
+                                                              uint16_t aDuration,
+                                                              nsISupports* aData,
+                                                              nsIRunnable* aCallback) {
+  auto data = static_cast<FullscreenTransitionData*>(aData);
+  FullscreenTransitionDelegate* delegate = [[FullscreenTransitionDelegate alloc] init];
+  delegate->mWindow = this;
+  // Storing already_AddRefed directly could cause static checking fail.
+  delegate->mCallback = nsCOMPtr<nsIRunnable>(aCallback).forget().take();
+
+  if (mFullscreenTransitionAnimation) {
+    [mFullscreenTransitionAnimation stopAnimation];
+    ReleaseFullscreenTransitionAnimation();
+  }
+
+  NSDictionary* dict = @{
+    NSViewAnimationTargetKey : data->mTransitionWindow,
+    NSViewAnimationEffectKey : aStage == eBeforeFullscreenToggle ? NSViewAnimationFadeInEffect
+                                                                 : NSViewAnimationFadeOutEffect
+  };
+  mFullscreenTransitionAnimation = [[NSViewAnimation alloc] initWithViewAnimations:@[ dict ]];
+  [mFullscreenTransitionAnimation setDelegate:delegate];
+  [mFullscreenTransitionAnimation setDuration:aDuration / 1000.0];
+  [mFullscreenTransitionAnimation startAnimation];
+}
+
+void nsCocoaWindow::CocoaWindowWillEnterFullscreen(bool aFullscreen) {
+  MOZ_ASSERT(mUpdateFullscreenOnResize.isNothing());
+
+  mHasStartedNativeFullscreen = true;
+
+  // Ensure that we update our fullscreen state as early as possible, when the resize
+  // happens.
+  mUpdateFullscreenOnResize =
+      Some(aFullscreen ? TransitionType::Fullscreen : TransitionType::Windowed);
+}
+
+void nsCocoaWindow::CocoaWindowDidEnterFullscreen(bool aFullscreen) {
+  mHasStartedNativeFullscreen = false;
+  DispatchOcclusionEvent();
+  HandleUpdateFullscreenOnResize();
+  FinishCurrentTransitionIfMatching(aFullscreen ? TransitionType::Fullscreen
+                                                : TransitionType::Windowed);
+}
+
+void nsCocoaWindow::CocoaWindowDidFailFullscreen(bool aAttemptedFullscreen) {
+  mHasStartedNativeFullscreen = false;
+  DispatchOcclusionEvent();
+
+  // If we already updated our fullscreen state due to a resize, we need to update it again.
+  if (mUpdateFullscreenOnResize.isNothing()) {
+    UpdateFullscreenState(!aAttemptedFullscreen, true);
+    ReportSizeEvent();
+  }
+
+  TransitionType transition =
+      aAttemptedFullscreen ? TransitionType::Fullscreen : TransitionType::Windowed;
+  FinishCurrentTransitionIfMatching(transition);
+}
+
+void nsCocoaWindow::UpdateFullscreenState(bool aFullScreen, bool aNativeMode) {
+  bool wasInFullscreen = mInFullScreenMode;
+  mInFullScreenMode = aFullScreen;
+  if (aNativeMode || mInNativeFullScreenMode) {
+    mInNativeFullScreenMode = aFullScreen;
+  }
+
+  if (aFullScreen == wasInFullscreen) {
+    return;
+  }
+
+  DispatchSizeModeEvent();
+
+  // Notify the mainChildView with our new fullscreen state.
+  nsChildView* mainChildView = static_cast<nsChildView*>([[mWindow mainChildView] widget]);
+  if (mainChildView) {
+    mainChildView->UpdateFullscreen(aFullScreen);
+  }
+}
+
+nsresult nsCocoaWindow::MakeFullScreen(bool aFullScreen) {
+  return DoMakeFullScreen(aFullScreen, AlwaysUsesNativeFullScreen());
+}
+
+nsresult nsCocoaWindow::MakeFullScreenWithNativeTransition(bool aFullScreen) {
+  return DoMakeFullScreen(aFullScreen, true);
+}
+
+nsresult nsCocoaWindow::DoMakeFullScreen(bool aFullScreen, bool aUseSystemTransition) {
+  if (!mWindow) {
+    return NS_OK;
+  }
+
+  // Figure out what type of transition is being requested.
+  TransitionType transition = TransitionType::Windowed;
+  if (aFullScreen) {
+    // Decide whether to use fullscreen or emulated fullscreen.
+    transition = (aUseSystemTransition &&
+                  (mWindow.collectionBehavior & NSWindowCollectionBehaviorFullScreenPrimary))
+                     ? TransitionType::Fullscreen
+                     : TransitionType::EmulatedFullscreen;
+  }
+
+  QueueTransition(transition);
+  return NS_OK;
+}
+
+void nsCocoaWindow::QueueTransition(const TransitionType& aTransition) {
+  mTransitionsPending.push(aTransition);
+  ProcessTransitions();
+}
+
+void nsCocoaWindow::ProcessTransitions() {
+  NS_OBJC_BEGIN_TRY_IGNORE_BLOCK
+
+  if (mInProcessTransitions) {
+    return;
+  }
+
+  mInProcessTransitions = true;
+
+  // Start a loop that will continue as long as we have transitions to process
+  // and we aren't waiting on an asynchronous transition to complete. Any
+  // transition that starts something async will `continue` this loop to exit.
+  while (!mTransitionsPending.empty() && !IsInTransition()) {
+    TransitionType nextTransition = mTransitionsPending.front();
+
+    // We have to check for some incompatible transition states, and if we find one,
+    // instead perform an alternative transition and leave the queue untouched. If
+    // we add one of these transitions, we set mIsTransitionCurrentAdded because we
+    // don't want to confuse listeners who are expecting to receive exactly one
+    // event when the requested transition has completed.
+    switch (nextTransition) {
+      case TransitionType::Fullscreen:
+      case TransitionType::EmulatedFullscreen:
+      case TransitionType::Windowed:
+      case TransitionType::Zoom:
+        // These can't handle miniaturized windows, so deminiaturize first.
+        if (mWindow.miniaturized) {
+          mTransitionCurrent = Some(TransitionType::Deminiaturize);
+          mIsTransitionCurrentAdded = true;
+        }
+        break;
+      case TransitionType::Miniaturize:
+        // This can't handle fullscreen, so go to windowed first.
+        if (mInFullScreenMode) {
+          mTransitionCurrent = Some(TransitionType::Windowed);
+          mIsTransitionCurrentAdded = true;
+        }
+        break;
+      default:
+        break;
+    }
+
+    // If mTransitionCurrent is still empty, then we use the nextTransition and pop
+    // the queue.
+    if (mTransitionCurrent.isNothing()) {
+      mTransitionCurrent = Some(nextTransition);
+      mTransitionsPending.pop();
+    }
+
+    switch (*mTransitionCurrent) {
+      case TransitionType::Fullscreen: {
+        if (!mInFullScreenMode) {
+          // This triggers an async animation, so continue.
+          [mWindow toggleFullScreen:nil];
+          continue;
+        }
+        break;
+      }
+
+      case TransitionType::EmulatedFullscreen: {
+        if (!mInFullScreenMode) {
+          NSDisableScreenUpdates();
+          mSuppressSizeModeEvents = true;
+          // The order here matters. When we exit full screen mode, we need to show the
+          // Dock first, otherwise the newly-created window won't have its minimize
+          // button enabled. See bug 526282.
+          nsCocoaUtils::HideOSChromeOnScreen(true);
+          nsBaseWidget::InfallibleMakeFullScreen(true);
+          mSuppressSizeModeEvents = false;
+          NSEnableScreenUpdates();
+          UpdateFullscreenState(true, false);
+        }
+        break;
+      }
+
+      case TransitionType::Windowed: {
+        if (mInFullScreenMode) {
+          if (mInNativeFullScreenMode) {
+            // This triggers an async animation, so continue.
+            [mWindow toggleFullScreen:nil];
+            continue;
+          } else {
+            NSDisableScreenUpdates();
+            mSuppressSizeModeEvents = true;
+            // The order here matters. When we exit full screen mode, we need to show the
+            // Dock first, otherwise the newly-created window won't have its minimize
+            // button enabled. See bug 526282.
+            nsCocoaUtils::HideOSChromeOnScreen(false);
+            nsBaseWidget::InfallibleMakeFullScreen(false);
+            mSuppressSizeModeEvents = false;
+            NSEnableScreenUpdates();
+            UpdateFullscreenState(false, false);
+          }
+        } else if (mWindow.zoomed) {
+          [mWindow zoom:nil];
+
+          // Check if we're still zoomed. If we are, we need to do *something* to make the
+          // window smaller than the zoom size so Cocoa will treat us as being out of the
+          // zoomed state. Otherwise, we could stay zoomed and never be able to be "normal"
+          // from calls to SetSizeMode.
+          if (mWindow.zoomed) {
+            NSRect maximumFrame = mWindow.frame;
+            const CGFloat INSET_OUT_OF_ZOOM = 20.0f;
+            [mWindow setFrame:NSInsetRect(maximumFrame, INSET_OUT_OF_ZOOM, INSET_OUT_OF_ZOOM)
+                      display:YES];
+            MOZ_ASSERT(!mWindow.zoomed,
+                       "We should be able to unzoom by shrinking the frame a bit.");
+          }
+        }
+        break;
+      }
+
+      case TransitionType::Miniaturize:
+        if (!mWindow.miniaturized) {
+          // This triggers an async animation, so continue.
+          [mWindow miniaturize:nil];
+          continue;
+        }
+        break;
+
+      case TransitionType::Deminiaturize:
+        if (mWindow.miniaturized) {
+          // This triggers an async animation, so continue.
+          [mWindow deminiaturize:nil];
+          continue;
+        }
+        break;
+
+      case TransitionType::Zoom:
+        if (!mWindow.zoomed) {
+          [mWindow zoom:nil];
+        }
+        break;
+
+      default:
+        break;
+    }
+
+    mTransitionCurrent.reset();
+    mIsTransitionCurrentAdded = false;
+  }
+
+  mInProcessTransitions = false;
+
+  // When we finish processing transitions, dispatch a size mode event to cover the
+  // cases where an inserted transition suppressed one, and the original transition
+  // never sent one because it detected it was at the desired state when it ran. If
+  // we've already sent a size mode event, then this will be a no-op.
+  if (!IsInTransition()) {
+    DispatchSizeModeEvent();
+  }
+
+  NS_OBJC_END_TRY_IGNORE_BLOCK;
+}
+
+void nsCocoaWindow::FinishCurrentTransition() {
+  mTransitionCurrent.reset();
+  mIsTransitionCurrentAdded = false;
+  ProcessTransitions();
+}
+
+void nsCocoaWindow::FinishCurrentTransitionIfMatching(const TransitionType& aTransition) {
+  // We've just finished some transition activity, and we're not sure whether it was
+  // triggered programmatically, or by the user. If it matches our current transition,
+  // then assume it was triggered programmatically and we can clean up that transition
+  // and start processing transitions again.
+
+  // Whether programmatic or user-initiated, we send out a size mode event.
+  DispatchSizeModeEvent();
+
+  if (mTransitionCurrent.isSome() && (*mTransitionCurrent == aTransition)) {
+    // This matches our current transition. Since this function is called from
+    // nsWindowDelegate transition callbacks, we want to make sure those callbacks are
+    // all the way done before we start processing more transitions. To accomplish this,
+    // we dispatch our cleanup to happen on the next event loop. Doing this will ensure
+    // that any async native transition methods we call (like toggleFullscreen) will
+    // succeed.
+    NS_DispatchToCurrentThread(NewRunnableMethod("FinishCurrentTransition", this,
+                                                 &nsCocoaWindow::FinishCurrentTransition));
+  }
+}
+
+bool nsCocoaWindow::HandleUpdateFullscreenOnResize() {
+  if (mUpdateFullscreenOnResize.isNothing()) {
+    return false;
+  }
+
+  bool toFullscreen = (*mUpdateFullscreenOnResize == TransitionType::Fullscreen);
+  mUpdateFullscreenOnResize.reset();
+  UpdateFullscreenState(toFullscreen, true);
+
+  return true;
+}
+
+// Coordinates are desktop pixels
+void nsCocoaWindow::DoResize(double aX, double aY, double aWidth, double aHeight, bool aRepaint,
+                             bool aConstrainToCurrentScreen) {
+  NS_OBJC_BEGIN_TRY_IGNORE_BLOCK;
+
+  if (!mWindow || mInResize) {
+    return;
+  }
+
+  // We are able to resize a window outside of any aspect ratio contraints
+  // applied to it, but in order to "update" the aspect ratio contraint to the
+  // new window dimensions, we must re-lock the aspect ratio.
+  auto relockAspectRatio = MakeScopeExit([&]() {
+    if (mAspectRatioLocked) {
+      LockAspectRatio(true);
+    }
+  });
+
+  AutoRestore<bool> reentrantResizeGuard(mInResize);
+  mInResize = true;
+
+  CGFloat scale = mSizeConstraints.mScale.scale;
+  if (scale == MOZ_WIDGET_INVALID_SCALE) {
+    scale = BackingScaleFactor();
+  }
+
+  // mSizeConstraints is in device pixels.
+  int32_t width = NSToIntRound(aWidth * scale);
+  int32_t height = NSToIntRound(aHeight * scale);
+
+  width =
+      std::max(mSizeConstraints.mMinSize.width, std::min(mSizeConstraints.mMaxSize.width, width));
+  height = std::max(mSizeConstraints.mMinSize.height,
+                    std::min(mSizeConstraints.mMaxSize.height, height));
+
+  DesktopIntRect newBounds(NSToIntRound(aX), NSToIntRound(aY), NSToIntRound(width / scale),
+                           NSToIntRound(height / scale));
+
+  // constrain to the screen that contains the largest area of the new rect
+  FitRectToVisibleAreaForScreen(newBounds, aConstrainToCurrentScreen ? [mWindow screen] : nullptr);
+
+  // convert requested bounds into Cocoa coordinate system
+  NSRect newFrame = nsCocoaUtils::GeckoRectToCocoaRect(newBounds);
+
+  NSRect frame = [mWindow frame];
+  BOOL isMoving = newFrame.origin.x != frame.origin.x || newFrame.origin.y != frame.origin.y;
+  BOOL isResizing =
+      newFrame.size.width != frame.size.width || newFrame.size.height != frame.size.height;
+
+  if (!isMoving && !isResizing) {
+    return;
+  }
+
+  // We ignore aRepaint -- we have to call display:YES, otherwise the
+  // title bar doesn't immediately get repainted and is displayed in
+  // the wrong place, leading to a visual jump.
+  [mWindow setFrame:newFrame display:YES];
+
+  NS_OBJC_END_TRY_IGNORE_BLOCK;
+}
+
+// Coordinates are desktop pixels
+void nsCocoaWindow::Resize(double aX, double aY, double aWidth, double aHeight, bool aRepaint) {
+  DoResize(aX, aY, aWidth, aHeight, aRepaint, false);
+}
+
+// Coordinates are desktop pixels
+void nsCocoaWindow::Resize(double aWidth, double aHeight, bool aRepaint) {
+  double invScale = 1.0 / BackingScaleFactor();
+  DoResize(mBounds.x * invScale, mBounds.y * invScale, aWidth, aHeight, aRepaint, true);
+}
+
+// Return the area that the Gecko ChildView in our window should cover, as an
+// NSRect in screen coordinates (with 0,0 being the bottom left corner of the
+// primary screen).
+NSRect nsCocoaWindow::GetClientCocoaRect() {
+  if (!mWindow) {
+    return NSZeroRect;
+  }
+
+  return [mWindow childViewRectForFrameRect:[mWindow frame]];
+}
+
+LayoutDeviceIntRect nsCocoaWindow::GetClientBounds() {
+  NS_OBJC_BEGIN_TRY_BLOCK_RETURN;
+
+  CGFloat scaleFactor = BackingScaleFactor();
+  return nsCocoaUtils::CocoaRectToGeckoRectDevPix(GetClientCocoaRect(), scaleFactor);
+
+  NS_OBJC_END_TRY_BLOCK_RETURN(LayoutDeviceIntRect(0, 0, 0, 0));
+}
+
+void nsCocoaWindow::UpdateBounds() {
+  NSRect frame = NSZeroRect;
+  if (mWindow) {
+    frame = [mWindow frame];
+  }
+  mBounds = nsCocoaUtils::CocoaRectToGeckoRectDevPix(frame, BackingScaleFactor());
+
+  if (mPopupContentView) {
+    mPopupContentView->UpdateBoundsFromView();
+  }
+}
+
+LayoutDeviceIntRect nsCocoaWindow::GetScreenBounds() {
+  NS_OBJC_BEGIN_TRY_BLOCK_RETURN;
+
+#ifdef DEBUG
+  LayoutDeviceIntRect r =
+      nsCocoaUtils::CocoaRectToGeckoRectDevPix([mWindow frame], BackingScaleFactor());
+  NS_ASSERTION(mWindow && mBounds == r, "mBounds out of sync!");
+#endif
+
+  return mBounds;
+
+  NS_OBJC_END_TRY_BLOCK_RETURN(LayoutDeviceIntRect(0, 0, 0, 0));
+}
+
+double nsCocoaWindow::GetDefaultScaleInternal() { return BackingScaleFactor(); }
+
+static CGFloat GetBackingScaleFactor(NSWindow* aWindow) {
+  NSRect frame = [aWindow frame];
+  if (frame.size.width > 0 && frame.size.height > 0) {
+    return nsCocoaUtils::GetBackingScaleFactor(aWindow);
+  }
+
+  // For windows with zero width or height, the backingScaleFactor method
+  // is broken - it will always return 2 on a retina macbook, even when
+  // the window position implies it's on a non-hidpi external display
+  // (to the extent that a zero-area window can be said to be "on" a
+  // display at all!)
+  // And to make matters worse, Cocoa even fires a
+  // windowDidChangeBackingProperties notification with the
+  // NSBackingPropertyOldScaleFactorKey key when a window on an
+  // external display is resized to/from zero height, even though it hasn't
+  // really changed screens.
+
+  // This causes us to handle popup window sizing incorrectly when the
+  // popup is resized to zero height (bug 820327) - nsXULPopupManager
+  // becomes (incorrectly) convinced the popup has been explicitly forced
+  // to a non-default size and needs to have size attributes attached.
+
+  // Workaround: instead of asking the window, we'll find the screen it is on
+  // and ask that for *its* backing scale factor.
+
+  // (See bug 853252 and additional comments in windowDidChangeScreen: below
+  // for further complications this causes.)
+
+  // First, expand the rect so that it actually has a measurable area,
+  // for FindTargetScreenForRect to use.
+  if (frame.size.width == 0) {
+    frame.size.width = 1;
+  }
+  if (frame.size.height == 0) {
+    frame.size.height = 1;
+  }
+
+  // Then identify the screen it belongs to, and return its scale factor.
+  NSScreen* screen = FindTargetScreenForRect(nsCocoaUtils::CocoaRectToGeckoRect(frame));
+  return nsCocoaUtils::GetBackingScaleFactor(screen);
+}
+
+CGFloat nsCocoaWindow::BackingScaleFactor() {
+  if (mBackingScaleFactor > 0.0) {
+    return mBackingScaleFactor;
+  }
+  if (!mWindow) {
+    return 1.0;
+  }
+  mBackingScaleFactor = GetBackingScaleFactor(mWindow);
+  return mBackingScaleFactor;
+}
+
+void nsCocoaWindow::BackingScaleFactorChanged() {
+  CGFloat newScale = GetBackingScaleFactor(mWindow);
+
+  // ignore notification if it hasn't really changed (or maybe we have
+  // disabled HiDPI mode via prefs)
+  if (mBackingScaleFactor == newScale) {
+    return;
+  }
+
+  mBackingScaleFactor = newScale;
+
+  if (!mWidgetListener || mWidgetListener->GetAppWindow()) {
+    return;
+  }
+
+  if (PresShell* presShell = mWidgetListener->GetPresShell()) {
+    presShell->BackingScaleFactorChanged();
+  }
+  mWidgetListener->UIResolutionChanged();
+}
+
+int32_t nsCocoaWindow::RoundsWidgetCoordinatesTo() {
+  if (BackingScaleFactor() == 2.0) {
+    return 2;
+  }
+  return 1;
+}
+
+void nsCocoaWindow::SetCursor(const Cursor& aCursor) {
+  if (mPopupContentView) {
+    mPopupContentView->SetCursor(aCursor);
+  }
+}
+
+nsresult nsCocoaWindow::SetTitle(const nsAString& aTitle) {
+  NS_OBJC_BEGIN_TRY_BLOCK_RETURN;
+
+  if (!mWindow) {
+    return NS_OK;
+  }
+
+  const nsString& strTitle = PromiseFlatString(aTitle);
+  const unichar* uniTitle = reinterpret_cast<const unichar*>(strTitle.get());
+  NSString* title = [NSString stringWithCharacters:uniTitle length:strTitle.Length()];
+  if ([mWindow drawsContentsIntoWindowFrame] && ![mWindow wantsTitleDrawn]) {
+    // Don't cause invalidations when the title isn't displayed.
+    [mWindow disableSetNeedsDisplay];
+    [mWindow setTitle:title];
+    [mWindow enableSetNeedsDisplay];
+  } else {
+    [mWindow setTitle:title];
+  }
+
+  return NS_OK;
+
+  NS_OBJC_END_TRY_BLOCK_RETURN(NS_ERROR_FAILURE);
+}
+
+void nsCocoaWindow::Invalidate(const LayoutDeviceIntRect& aRect) {
+  if (mPopupContentView) {
+    mPopupContentView->Invalidate(aRect);
+  }
+}
+
+// Pass notification of some drag event to Gecko
+//
+// The drag manager has let us know that something related to a drag has
+// occurred in this window. It could be any number of things, ranging from
+// a drop, to a drag enter/leave, or a drag over event. The actual event
+// is passed in |aMessage| and is passed along to our event hanlder so Gecko
+// knows about it.
+bool nsCocoaWindow::DragEvent(unsigned int aMessage, mozilla::gfx::Point aMouseGlobal,
+                              UInt16 aKeyModifiers) {
+  return false;
+}
+
+NS_IMETHODIMP nsCocoaWindow::SendSetZLevelEvent() {
+  nsWindowZ placement = nsWindowZTop;
+  nsCOMPtr<nsIWidget> actualBelow;
+  if (mWidgetListener)
+    mWidgetListener->ZLevelChanged(true, &placement, nullptr, getter_AddRefs(actualBelow));
+  return NS_OK;
+}
+
+NS_IMETHODIMP nsCocoaWindow::GetChildSheet(bool aShown, nsIWidget** _retval) {
+  nsIWidget* child = GetFirstChild();
+
+  while (child) {
+    if (child->GetWindowType() == WindowType::Sheet) {
+      // if it's a sheet, it must be an nsCocoaWindow
+      nsCocoaWindow* cocoaWindow = static_cast<nsCocoaWindow*>(child);
+      if (cocoaWindow->mWindow && ((aShown && [cocoaWindow->mWindow isVisible]) ||
+                                   (!aShown && cocoaWindow->mSheetNeedsShow))) {
+        nsCOMPtr<nsIWidget> widget = cocoaWindow;
+        widget.forget(_retval);
+        return NS_OK;
+      }
+    }
+    child = child->GetNextSibling();
+  }
+
+  *_retval = nullptr;
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP nsCocoaWindow::GetRealParent(nsIWidget** parent) {
+  *parent = mParent;
+  return NS_OK;
+}
+
+NS_IMETHODIMP nsCocoaWindow::GetIsSheet(bool* isSheet) {
+  mWindowType == WindowType::Sheet ? * isSheet = true : * isSheet = false;
+  return NS_OK;
+}
+
+NS_IMETHODIMP nsCocoaWindow::GetSheetWindowParent(NSWindow** sheetWindowParent) {
+  *sheetWindowParent = mSheetWindowParent;
+  return NS_OK;
+}
+
+// Invokes callback and ProcessEvent methods on Event Listener object
+nsresult nsCocoaWindow::DispatchEvent(WidgetGUIEvent* event, nsEventStatus& aStatus) {
+  aStatus = nsEventStatus_eIgnore;
+
+  nsCOMPtr<nsIWidget> kungFuDeathGrip(event->mWidget);
+  mozilla::Unused << kungFuDeathGrip;  // Not used within this function
+
+  if (mWidgetListener) aStatus = mWidgetListener->HandleEvent(event, mUseAttachedEvents);
+
+  return NS_OK;
+}
+
+// aFullScreen should be the window's mInFullScreenMode. We don't have access to that
+// from here, so we need to pass it in. mInFullScreenMode should be the canonical
+// indicator that a window is currently full screen and it makes sense to keep
+// all sizemode logic here.
+static nsSizeMode GetWindowSizeMode(NSWindow* aWindow, bool aFullScreen) {
+  if (aFullScreen) return nsSizeMode_Fullscreen;
+  if ([aWindow isMiniaturized]) return nsSizeMode_Minimized;
+  if (([aWindow styleMask] & NSWindowStyleMaskResizable) && [aWindow isZoomed])
+    return nsSizeMode_Maximized;
+  return nsSizeMode_Normal;
+}
+
+void nsCocoaWindow::ReportMoveEvent() {
+  NS_OBJC_BEGIN_TRY_IGNORE_BLOCK;
+
+  // Prevent recursion, which can become infinite (see bug 708278).  This
+  // can happen when the call to [NSWindow setFrameTopLeftPoint:] in
+  // nsCocoaWindow::Move() triggers an immediate NSWindowDidMove notification
+  // (and a call to [WindowDelegate windowDidMove:]).
+  if (mInReportMoveEvent) {
+    return;
+  }
+  mInReportMoveEvent = true;
+
+  UpdateBounds();
+
+  // The zoomed state can change when we're moving, in which case we need to
+  // update our internal mSizeMode. This can happen either if we're maximized
+  // and then moved, or if we're not maximized and moved back to zoomed state.
+  if (mWindow && ((mSizeMode == nsSizeMode_Maximized) ^ [mWindow isZoomed])) {
+    DispatchSizeModeEvent();
+  }
+
+  // Dispatch the move event to Gecko
+  NotifyWindowMoved(mBounds.x, mBounds.y);
+
+  mInReportMoveEvent = false;
+
+  NS_OBJC_END_TRY_IGNORE_BLOCK;
+}
+
+void nsCocoaWindow::DispatchSizeModeEvent() {
+  if (!mWindow) {
+    return;
+  }
+
+  if (mSuppressSizeModeEvents || mIsTransitionCurrentAdded) {
+    return;
+  }
+
+  nsSizeMode newMode = GetWindowSizeMode(mWindow, mInFullScreenMode);
+  if (mSizeMode == newMode) {
+    return;
+  }
+
+  mSizeMode = newMode;
+  if (mWidgetListener) {
+    mWidgetListener->SizeModeChanged(newMode);
+  }
+
+  if (StaticPrefs::widget_pause_compositor_when_minimized()) {
+    if (newMode == nsSizeMode_Minimized) {
+      PauseCompositor();
+    } else {
+      ResumeCompositor();
+    }
+  }
+}
+
+void nsCocoaWindow::DispatchOcclusionEvent() {
+  if (!mWindow) {
+    return;
+  }
+
+  // Our new occlusion state is true if the window is not visible.
+  bool newOcclusionState =
+      !(mHasStartedNativeFullscreen || ([mWindow occlusionState] & NSWindowOcclusionStateVisible));
+
+  // Don't dispatch if the new occlustion state is the same as the current state.
+  if (mIsFullyOccluded == newOcclusionState) {
+    return;
+  }
+
+  MOZ_ASSERT(mIgnoreOcclusionCount >= 0);
+  if (newOcclusionState && mIgnoreOcclusionCount > 0) {
+    return;
+  }
+
+  mIsFullyOccluded = newOcclusionState;
+  if (mWidgetListener) {
+    mWidgetListener->OcclusionStateChanged(mIsFullyOccluded);
+  }
+}
+
+void nsCocoaWindow::ReportSizeEvent() {
+  NS_OBJC_BEGIN_TRY_IGNORE_BLOCK;
+
+  UpdateBounds();
+  if (mWidgetListener) {
+    LayoutDeviceIntRect innerBounds = GetClientBounds();
+    mWidgetListener->WindowResized(this, innerBounds.width, innerBounds.height);
+  }
+
+  NS_OBJC_END_TRY_IGNORE_BLOCK;
+}
+
+void nsCocoaWindow::PauseCompositor() {
+  nsIWidget* mainChildView = static_cast<nsIWidget*>([[mWindow mainChildView] widget]);
+  if (!mainChildView) {
+    return;
+  }
+  CompositorBridgeChild* remoteRenderer = mainChildView->GetRemoteRenderer();
+  if (!remoteRenderer) {
+    return;
+  }
+  remoteRenderer->SendPause();
+}
+
+void nsCocoaWindow::ResumeCompositor() {
+  nsIWidget* mainChildView = static_cast<nsIWidget*>([[mWindow mainChildView] widget]);
+  if (!mainChildView) {
+    return;
+  }
+  CompositorBridgeChild* remoteRenderer = mainChildView->GetRemoteRenderer();
+  if (!remoteRenderer) {
+    return;
+  }
+  remoteRenderer->SendResume();
+}
+
+void nsCocoaWindow::SetMenuBar(RefPtr<nsMenuBarX>&& aMenuBar) {
+  if (!mWindow) {
+    mMenuBar = nullptr;
+    return;
+  }
+  mMenuBar = std::move(aMenuBar);
+
+  // Only paint for active windows, or paint the hidden window menu bar if no
+  // other menu bar has been painted yet so that some reasonable menu bar is
+  // displayed when the app starts up.
+  if (mMenuBar && ((!gSomeMenuBarPainted && nsMenuUtilsX::GetHiddenWindowMenuBar() == mMenuBar) ||
+                   [mWindow isMainWindow]))
+    mMenuBar->Paint();
+}
+
+void nsCocoaWindow::SetFocus(Raise aRaise, mozilla::dom::CallerType aCallerType) {
+  if (!mWindow) return;
+
+  if (mPopupContentView) {
+    return mPopupContentView->SetFocus(aRaise, aCallerType);
+  }
+
+  if (aRaise == Raise::Yes && ([mWindow isVisible] || [mWindow isMiniaturized])) {
+    if ([mWindow isMiniaturized]) {
+      [mWindow deminiaturize:nil];
+    }
+
+    [mWindow makeKeyAndOrderFront:nil];
+    SendSetZLevelEvent();
+  }
+}
+
+LayoutDeviceIntPoint nsCocoaWindow::WidgetToScreenOffset() {
+  NS_OBJC_BEGIN_TRY_BLOCK_RETURN;
+
+  return nsCocoaUtils::CocoaRectToGeckoRectDevPix(GetClientCocoaRect(), BackingScaleFactor())
+      .TopLeft();
+
+  NS_OBJC_END_TRY_BLOCK_RETURN(LayoutDeviceIntPoint(0, 0));
+}
+
+LayoutDeviceIntPoint nsCocoaWindow::GetClientOffset() {
+  NS_OBJC_BEGIN_TRY_BLOCK_RETURN;
+
+  LayoutDeviceIntRect clientRect = GetClientBounds();
+
+  return clientRect.TopLeft() - mBounds.TopLeft();
+
+  NS_OBJC_END_TRY_BLOCK_RETURN(LayoutDeviceIntPoint(0, 0));
+}
+
+LayoutDeviceIntMargin nsCocoaWindow::ClientToWindowMargin() {
+  NS_OBJC_BEGIN_TRY_BLOCK_RETURN;
+
+  if (!mWindow || mWindow.drawsContentsIntoWindowFrame || mWindowType == WindowType::Popup) {
+    return {};
+  }
+
+  NSRect clientNSRect = mWindow.contentLayoutRect;
+  NSRect frameNSRect = [mWindow frameRectForChildViewRect:clientNSRect];
+
+  CGFloat backingScale = BackingScaleFactor();
+  const auto clientRect = nsCocoaUtils::CocoaRectToGeckoRectDevPix(clientNSRect, backingScale);
+  const auto frameRect = nsCocoaUtils::CocoaRectToGeckoRectDevPix(frameNSRect, backingScale);
+
+  return frameRect - clientRect;
+
+  NS_OBJC_END_TRY_BLOCK_RETURN({});
+}
+
+nsMenuBarX* nsCocoaWindow::GetMenuBar() { return mMenuBar; }
+
+void nsCocoaWindow::CaptureRollupEvents(bool aDoCapture) {
+  NS_OBJC_BEGIN_TRY_IGNORE_BLOCK;
+
+  if (aDoCapture) {
+    if (![NSApp isActive]) {
+      // We need to capture mouse event if we aren't
+      // the active application. We only set this up when needed
+      // because they cause spurious mouse event after crash
+      // and gdb sessions. See bug 699538.
+      nsToolkit::GetToolkit()->MonitorAllProcessMouseEvents();
+    }
+
+    // Sometimes more than one popup window can be visible at the same time
+    // (e.g. nested non-native context menus, or the test case (attachment
+    // 276885) for bmo bug 392389, which displays a non-native combo-box in a
+    // non-native popup window).  In these cases the "active" popup window should
+    // be the topmost -- the (nested) context menu the mouse is currently over,
+    // or the combo-box's drop-down list (when it's displayed).  But (among
+    // windows that have the same "level") OS X makes topmost the window that
+    // last received a mouse-down event, which may be incorrect (in the combo-
+    // box case, it makes topmost the window containing the combo-box).  So
+    // here we fiddle with a non-native popup window's level to make sure the
+    // "active" one is always above any other non-native popup windows that
+    // may be visible.
+    if (mWindow && (mWindowType == WindowType::Popup)) SetPopupWindowLevel();
+  } else {
+    nsToolkit::GetToolkit()->StopMonitoringAllProcessMouseEvents();
+
+    // XXXndeakin this doesn't make sense.
+    // Why is the new window assumed to be a modal panel?
+    if (mWindow && (mWindowType == WindowType::Popup)) [mWindow setLevel:NSModalPanelWindowLevel];
+  }
+
+  NS_OBJC_END_TRY_IGNORE_BLOCK;
+}
+
+nsresult nsCocoaWindow::GetAttention(int32_t aCycleCount) {
+  NS_OBJC_BEGIN_TRY_BLOCK_RETURN;
+
+  [NSApp requestUserAttention:NSInformationalRequest];
+  return NS_OK;
+
+  NS_OBJC_END_TRY_BLOCK_RETURN(NS_ERROR_FAILURE);
+}
+
+bool nsCocoaWindow::HasPendingInputEvent() { return nsChildView::DoHasPendingInputEvent(); }
+
+void nsCocoaWindow::SetWindowShadowStyle(StyleWindowShadow aStyle) {
+  NS_OBJC_BEGIN_TRY_IGNORE_BLOCK;
+
+  mShadowStyle = aStyle;
+
+  if (!mWindow || mWindowType != WindowType::Popup) {
+    return;
+  }
+
+  mWindow.shadowStyle = mShadowStyle;
+  [mWindow setUseMenuStyle:mShadowStyle == StyleWindowShadow::Menu];
+  [mWindow setHasShadow:aStyle != StyleWindowShadow::None];
+
+  NS_OBJC_END_TRY_IGNORE_BLOCK;
+}
+
+void nsCocoaWindow::SetWindowOpacity(float aOpacity) {
+  NS_OBJC_BEGIN_TRY_IGNORE_BLOCK;
+
+  if (!mWindow) {
+    return;
+  }
+
+  [mWindow setAlphaValue:(CGFloat)aOpacity];
+
+  NS_OBJC_END_TRY_IGNORE_BLOCK;
+}
+
+void nsCocoaWindow::SetColorScheme(const Maybe<ColorScheme>& aScheme) {
+  NS_OBJC_BEGIN_TRY_IGNORE_BLOCK;
+
+  if (!mWindow) {
+    return;
+  }
+
+  mWindow.appearance = aScheme ? NSAppearanceForColorScheme(*aScheme) : nil;
+
+  NS_OBJC_END_TRY_IGNORE_BLOCK;
+}
+
+static inline CGAffineTransform GfxMatrixToCGAffineTransform(const gfx::Matrix& m) {
+  CGAffineTransform t;
+  t.a = m._11;
+  t.b = m._12;
+  t.c = m._21;
+  t.d = m._22;
+  t.tx = m._31;
+  t.ty = m._32;
+  return t;
+}
+
+void nsCocoaWindow::SetWindowTransform(const gfx::Matrix& aTransform) {
+  NS_OBJC_BEGIN_TRY_IGNORE_BLOCK;
+
+  if (!mWindow) {
+    return;
+  }
+
+  // Calling CGSSetWindowTransform when the window is not visible results in
+  // misplacing the window into doubled x,y coordinates (see bug 1448132).
+  if (![mWindow isVisible] || NSIsEmptyRect([mWindow frame])) {
+    return;
+  }
+
+  if (StaticPrefs::widget_window_transforms_disabled()) {
+    // CGSSetWindowTransform is a private API. In case calling it causes
+    // problems either now or in the future, we'll want to have an easy kill
+    // switch. So we allow disabling it with a pref.
+    return;
+  }
+
+  gfx::Matrix transform = aTransform;
+
+  // aTransform is a transform that should be applied to the window relative
+  // to its regular position: If aTransform._31 is 100, then we want the
+  // window to be displayed 100 pixels to the right of its regular position.
+  // The transform that CGSSetWindowTransform accepts has a different meaning:
+  // It's used to answer the question "For the screen pixel at x,y (with the
+  // origin at the top left), what pixel in the window's buffer (again with
+  // origin top left) should be displayed at that position?"
+  // In the example above, this means that we need to call
+  // CGSSetWindowTransform with a horizontal translation of -windowPos.x - 100.
+  // So we need to invert the transform and adjust it by the window's position.
+  if (!transform.Invert()) {
+    // Treat non-invertible transforms as the identity transform.
+    transform = gfx::Matrix();
+  }
+
+  bool isIdentity = transform.IsIdentity();
+  if (isIdentity && mWindowTransformIsIdentity) {
+    return;
+  }
+
+  transform.PreTranslate(-mBounds.x, -mBounds.y);
+
+  // Snap translations to device pixels, to match what we do for CSS transforms
+  // and because the window server rounds down instead of to nearest.
+  if (!transform.HasNonTranslation() && transform.HasNonIntegerTranslation()) {
+    auto snappedTranslation = gfx::IntPoint::Round(transform.GetTranslation());
+    transform = gfx::Matrix::Translation(snappedTranslation.x, snappedTranslation.y);
+  }
+
+  // We also need to account for the backing scale factor: aTransform is given
+  // in device pixels, but CGSSetWindowTransform works with logical display
+  // pixels.
+  CGFloat backingScale = BackingScaleFactor();
+  transform.PreScale(backingScale, backingScale);
+  transform.PostScale(1 / backingScale, 1 / backingScale);
+
+  CGSConnection cid = _CGSDefaultConnection();
+  CGSSetWindowTransform(cid, [mWindow windowNumber], GfxMatrixToCGAffineTransform(transform));
+
+  mWindowTransformIsIdentity = isIdentity;
+
+  NS_OBJC_END_TRY_IGNORE_BLOCK;
+}
+
+void nsCocoaWindow::SetInputRegion(const InputRegion& aInputRegion) {
+  MOZ_ASSERT(mWindowType == WindowType::Popup, "This should only be called on popup windows.");
+  // TODO: Somehow support aInputRegion.mMargin? Though maybe not.
+  if (aInputRegion.mFullyTransparent) {
+    [mWindow setIgnoresMouseEvents:YES];
+  } else {
+    [mWindow setIgnoresMouseEvents:NO];
+  }
+}
+
+void nsCocoaWindow::SetShowsToolbarButton(bool aShow) {
+  NS_OBJC_BEGIN_TRY_IGNORE_BLOCK;
+
+  if (mWindow) [mWindow setShowsToolbarButton:aShow];
+
+  NS_OBJC_END_TRY_IGNORE_BLOCK;
+}
+
+void nsCocoaWindow::SetSupportsNativeFullscreen(bool aSupportsNativeFullscreen) {
+  NS_OBJC_BEGIN_TRY_IGNORE_BLOCK;
+
+  if (mWindow) {
+    // This determines whether we tell cocoa that the window supports native
+    // full screen. If we do so, and another window is in native full screen,
+    // this window will also appear in native full screen. We generally only
+    // want to do this for primary application windows. We'll set the
+    // relevant macnativefullscreen attribute on those, which will lead to us
+    // being called with aSupportsNativeFullscreen set to `true` here.
+    NSWindowCollectionBehavior newBehavior = [mWindow collectionBehavior];
+    if (aSupportsNativeFullscreen) {
+      newBehavior |= NSWindowCollectionBehaviorFullScreenPrimary;
+    } else {
+      newBehavior &= ~NSWindowCollectionBehaviorFullScreenPrimary;
+    }
+    [mWindow setCollectionBehavior:newBehavior];
+  }
+
+  NS_OBJC_END_TRY_IGNORE_BLOCK;
+}
+
+void nsCocoaWindow::SetWindowAnimationType(nsIWidget::WindowAnimationType aType) {
+  mAnimationType = aType;
+}
+
+void nsCocoaWindow::SetDrawsTitle(bool aDrawTitle) {
+  NS_OBJC_BEGIN_TRY_IGNORE_BLOCK;
+
+  if (![mWindow drawsContentsIntoWindowFrame]) {
+    // If we don't draw into the window frame, we always want to display window
+    // titles.
+    [mWindow setWantsTitleDrawn:YES];
+  } else {
+    [mWindow setWantsTitleDrawn:aDrawTitle];
+  }
+
+  NS_OBJC_END_TRY_IGNORE_BLOCK;
+}
+
+nsresult nsCocoaWindow::SetNonClientMargins(const LayoutDeviceIntMargin& margins) {
+  NS_OBJC_BEGIN_TRY_BLOCK_RETURN;
+
+  SetDrawsInTitlebar(margins.top == 0);
+
+  return NS_OK;
+
+  NS_OBJC_END_TRY_BLOCK_RETURN(NS_ERROR_FAILURE);
+}
+
+void nsCocoaWindow::SetDrawsInTitlebar(bool aState) {
+  NS_OBJC_BEGIN_TRY_IGNORE_BLOCK;
+
+  if (mWindow) {
+    [mWindow setDrawsContentsIntoWindowFrame:aState];
+  }
+
+  NS_OBJC_END_TRY_IGNORE_BLOCK;
+}
+
+NS_IMETHODIMP nsCocoaWindow::SynthesizeNativeMouseEvent(LayoutDeviceIntPoint aPoint,
+                                                        NativeMouseMessage aNativeMessage,
+                                                        MouseButton aButton,
+                                                        nsIWidget::Modifiers aModifierFlags,
+                                                        nsIObserver* aObserver) {
+  NS_OBJC_BEGIN_TRY_BLOCK_RETURN;
+
+  AutoObserverNotifier notifier(aObserver, "mouseevent");
+  if (mPopupContentView) {
+    return mPopupContentView->SynthesizeNativeMouseEvent(aPoint, aNativeMessage, aButton,
+                                                         aModifierFlags, nullptr);
+  }
+
+  return NS_OK;
+
+  NS_OBJC_END_TRY_BLOCK_RETURN(NS_ERROR_FAILURE);
+}
+
+NS_IMETHODIMP nsCocoaWindow::SynthesizeNativeMouseScrollEvent(
+    LayoutDeviceIntPoint aPoint, uint32_t aNativeMessage, double aDeltaX, double aDeltaY,
+    double aDeltaZ, uint32_t aModifierFlags, uint32_t aAdditionalFlags, nsIObserver* aObserver) {
+  NS_OBJC_BEGIN_TRY_BLOCK_RETURN;
+
+  AutoObserverNotifier notifier(aObserver, "mousescrollevent");
+  if (mPopupContentView) {
+    // Pass nullptr as the observer so that the AutoObserverNotification in
+    // nsChildView::SynthesizeNativeMouseScrollEvent will be ignored.
+    return mPopupContentView->SynthesizeNativeMouseScrollEvent(aPoint, aNativeMessage, aDeltaX,
+                                                               aDeltaY, aDeltaZ, aModifierFlags,
+                                                               aAdditionalFlags, nullptr);
+  }
+
+  return NS_OK;
+
+  NS_OBJC_END_TRY_BLOCK_RETURN(NS_ERROR_FAILURE);
+}
+
+void nsCocoaWindow::LockAspectRatio(bool aShouldLock) {
+  NS_OBJC_BEGIN_TRY_IGNORE_BLOCK;
+
+  if (aShouldLock) {
+    [mWindow setContentAspectRatio:mWindow.frame.size];
+    mAspectRatioLocked = true;
+  } else {
+    // According to https://developer.apple.com/documentation/appkit/nswindow/1419507-aspectratio,
+    // aspect ratios and resize increments are mutually exclusive, and the accepted way of
+    // cancelling an established aspect ratio is to set the resize increments to 1.0, 1.0
+    [mWindow setResizeIncrements:NSMakeSize(1.0, 1.0)];
+    mAspectRatioLocked = false;
+  }
+
+  NS_OBJC_END_TRY_IGNORE_BLOCK;
+}
+
+void nsCocoaWindow::UpdateThemeGeometries(const nsTArray<ThemeGeometry>& aThemeGeometries) {
+  NS_OBJC_BEGIN_TRY_IGNORE_BLOCK;
+
+  if (mPopupContentView) {
+    return mPopupContentView->UpdateThemeGeometries(aThemeGeometries);
+  }
+
+  NS_OBJC_END_TRY_IGNORE_BLOCK;
+}
+
+void nsCocoaWindow::SetPopupWindowLevel() {
+  if (!mWindow) return;
+
+  // Floating popups are at the floating level and hide when the window is
+  // deactivated.
+  if (mPopupLevel == PopupLevel::Floating) {
+    [mWindow setLevel:NSFloatingWindowLevel];
+    [mWindow setHidesOnDeactivate:YES];
+  } else {
+    // Otherwise, this is a top-level or parent popup. Parent popups always
+    // appear just above their parent and essentially ignore the level.
+    [mWindow setLevel:NSPopUpMenuWindowLevel];
+    [mWindow setHidesOnDeactivate:NO];
+  }
+}
+
+void nsCocoaWindow::SetInputContext(const InputContext& aContext,
+                                    const InputContextAction& aAction) {
+  NS_OBJC_BEGIN_TRY_IGNORE_BLOCK;
+
+  mInputContext = aContext;
+
+  NS_OBJC_END_TRY_IGNORE_BLOCK;
+}
+
+bool nsCocoaWindow::GetEditCommands(NativeKeyBindingsType aType, const WidgetKeyboardEvent& aEvent,
+                                    nsTArray<CommandInt>& aCommands) {
+  // Validate the arguments.
+  if (NS_WARN_IF(!nsIWidget::GetEditCommands(aType, aEvent, aCommands))) {
+    return false;
+  }
+
+  NativeKeyBindings* keyBindings = NativeKeyBindings::GetInstance(aType);
+  // When the keyboard event is fired from this widget, it must mean that no web content has focus
+  // because any web contents should be on `nsChildView`.  And in any locales, the system UI is
+  // always horizontal layout.  So, let's pass `Nothing()` for the writing mode here, it won't be
+  // treated as in a vertical content.
+  keyBindings->GetEditCommands(aEvent, Nothing(), aCommands);
+  return true;
+}
+
+bool nsCocoaWindow::AsyncPanZoomEnabled() const {
+  if (mPopupContentView) {
+    return mPopupContentView->AsyncPanZoomEnabled();
+  }
+  return nsBaseWidget::AsyncPanZoomEnabled();
+}
+
+bool nsCocoaWindow::StartAsyncAutoscroll(const ScreenPoint& aAnchorLocation,
+                                         const ScrollableLayerGuid& aGuid) {
+  if (mPopupContentView) {
+    return mPopupContentView->StartAsyncAutoscroll(aAnchorLocation, aGuid);
+  }
+  return nsBaseWidget::StartAsyncAutoscroll(aAnchorLocation, aGuid);
+}
+
+void nsCocoaWindow::StopAsyncAutoscroll(const ScrollableLayerGuid& aGuid) {
+  if (mPopupContentView) {
+    mPopupContentView->StopAsyncAutoscroll(aGuid);
+    return;
+  }
+  nsBaseWidget::StopAsyncAutoscroll(aGuid);
+}
+
+already_AddRefed<nsIWidget> nsIWidget::CreateTopLevelWindow() {
+  nsCOMPtr<nsIWidget> window = new nsCocoaWindow();
+  return window.forget();
+}
+
+already_AddRefed<nsIWidget> nsIWidget::CreateChildWindow() {
+  nsCOMPtr<nsIWidget> window = new nsChildView();
+  return window.forget();
+}
+
+@implementation WindowDelegate
+
+// We try to find a gecko menu bar to paint. If one does not exist, just paint
+// the application menu by itself so that a window doesn't have some other
+// window's menu bar.
++ (void)paintMenubarForWindow:(NSWindow*)aWindow {
+  NS_OBJC_BEGIN_TRY_IGNORE_BLOCK;
+
+  // make sure we only act on windows that have this kind of
+  // object as a delegate
+  id windowDelegate = [aWindow delegate];
+  if ([windowDelegate class] != [self class]) return;
+
+  nsCocoaWindow* geckoWidget = [windowDelegate geckoWidget];
+  NS_ASSERTION(geckoWidget, "Window delegate not returning a gecko widget!");
+
+  nsMenuBarX* geckoMenuBar = geckoWidget->GetMenuBar();
+  if (geckoMenuBar) {
+    geckoMenuBar->Paint();
+  } else {
+    // sometimes we don't have a native application menu early in launching
+    if (!sApplicationMenu) return;
+
+    NSMenu* mainMenu = [NSApp mainMenu];
+    NS_ASSERTION([mainMenu numberOfItems] > 0,
+                 "Main menu does not have any items, something is terribly wrong!");
+
+    // Create a new menu bar.
+    // We create a GeckoNSMenu because all menu bar NSMenu objects should use that subclass for
+    // key handling reasons.
+    GeckoNSMenu* newMenuBar = [[GeckoNSMenu alloc] initWithTitle:@"MainMenuBar"];
+
+    // move the application menu from the existing menu bar to the new one
+    NSMenuItem* firstMenuItem = [[mainMenu itemAtIndex:0] retain];
+    [mainMenu removeItemAtIndex:0];
+    [newMenuBar insertItem:firstMenuItem atIndex:0];
+    [firstMenuItem release];
+
+    // set our new menu bar as the main menu
+    [NSApp setMainMenu:newMenuBar];
+    [newMenuBar release];
+  }
+
+  NS_OBJC_END_TRY_IGNORE_BLOCK;
+}
+
+- (id)initWithGeckoWindow:(nsCocoaWindow*)geckoWind {
+  NS_OBJC_BEGIN_TRY_BLOCK_RETURN;
+
+  [super init];
+  mGeckoWindow = geckoWind;
+  mToplevelActiveState = false;
+  mHasEverBeenZoomed = false;
+  return self;
+
+  NS_OBJC_END_TRY_BLOCK_RETURN(nil);
+}
+
+- (NSSize)windowWillResize:(NSWindow*)sender toSize:(NSSize)proposedFrameSize {
+  RollUpPopups();
+  return proposedFrameSize;
+}
+
+- (NSRect)windowWillUseStandardFrame:(NSWindow*)window defaultFrame:(NSRect)newFrame {
+  // This function needs to return a rect representing the frame a window would
+  // have if it is in its "maximized" size mode. The parameter newFrame is supposed
+  // to be a frame representing the maximum window size on the screen where the
+  // window currently appears. However, in practice, newFrame can be a much smaller
+  // size. So, we ignore newframe and instead return the frame of the entire screen
+  // associated with the window. That frame is bigger than the window could actually
+  // be, due to the presence of the menubar and possibly the dock, but we never call
+  // this function directly, and Cocoa callers will shrink it to its true maximum
+  // size.
+  return window.screen.frame;
+}
+
+void nsCocoaWindow::CocoaSendToplevelActivateEvents() {
+  if (mWidgetListener) {
+    mWidgetListener->WindowActivated();
+  }
+}
+
+void nsCocoaWindow::CocoaSendToplevelDeactivateEvents() {
+  if (mWidgetListener) {
+    mWidgetListener->WindowDeactivated();
+  }
+}
+
+void nsCocoaWindow::CocoaWindowDidResize() {
+  // It's important to update our bounds before we trigger any listeners. This
+  // ensures that our bounds are correct when GetScreenBounds is called.
+  UpdateBounds();
+
+  if (HandleUpdateFullscreenOnResize()) {
+    ReportSizeEvent();
+    return;
+  }
+
+  // Resizing might have changed our zoom state.
+  DispatchSizeModeEvent();
+  ReportSizeEvent();
+}
+
+- (void)windowDidResize:(NSNotification*)aNotification {
+  BaseWindow* window = [aNotification object];
+  [window updateTrackingArea];
+
+  if (!mGeckoWindow) return;
+
+  mGeckoWindow->CocoaWindowDidResize();
+}
+
+- (void)windowDidChangeScreen:(NSNotification*)aNotification {
+  if (!mGeckoWindow) return;
+
+  // Because of Cocoa's peculiar treatment of zero-size windows (see comments
+  // at GetBackingScaleFactor() above), we sometimes have a situation where
+  // our concept of backing scale (based on the screen where the zero-sized
+  // window is positioned) differs from Cocoa's idea (always based on the
+  // Retina screen, AFAICT, even when an external non-Retina screen is the
+  // primary display).
+  //
+  // As a result, if the window was created with zero size on an external
+  // display, but then made visible on the (secondary) Retina screen, we
+  // will *not* get a windowDidChangeBackingProperties notification for it.
+  // This leads to an incorrect GetDefaultScale(), and widget coordinate
+  // confusion, as per bug 853252.
+  //
+  // To work around this, we check for a backing scale mismatch when we
+  // receive a windowDidChangeScreen notification, as we will receive this
+  // even if Cocoa was already treating the zero-size window as having
+  // Retina backing scale.
+  NSWindow* window = (NSWindow*)[aNotification object];
+  if ([window respondsToSelector:@selector(backingScaleFactor)]) {
+    if (GetBackingScaleFactor(window) != mGeckoWindow->BackingScaleFactor()) {
+      mGeckoWindow->BackingScaleFactorChanged();
+    }
+  }
+
+  mGeckoWindow->ReportMoveEvent();
+}
+
+- (void)windowWillEnterFullScreen:(NSNotification*)notification {
+  if (!mGeckoWindow) {
+    return;
+  }
+  mGeckoWindow->CocoaWindowWillEnterFullscreen(true);
+}
+
+// Lion's full screen mode will bypass our internal fullscreen tracking, so
+// we need to catch it when we transition and call our own methods, which in
+// turn will fire "fullscreen" events.
+- (void)windowDidEnterFullScreen:(NSNotification*)notification {
+  // On Yosemite, the NSThemeFrame class has two new properties --
+  // titlebarView (an NSTitlebarView object) and titlebarContainerView (an
+  // NSTitlebarContainerView object).  These are used to display the titlebar
+  // in fullscreen mode.  In Safari they're not transparent.  But in Firefox
+  // for some reason they are, which causes bug 1069658.  The following code
+  // works around this Apple bug or design flaw.
+  NSWindow* window = (NSWindow*)[notification object];
+  NSView* frameView = [[window contentView] superview];
+  NSView* titlebarView = nil;
+  NSView* titlebarContainerView = nil;
+  if ([frameView respondsToSelector:@selector(titlebarView)]) {
+    titlebarView = [frameView titlebarView];
+  }
+  if ([frameView respondsToSelector:@selector(titlebarContainerView)]) {
+    titlebarContainerView = [frameView titlebarContainerView];
+  }
+  if ([titlebarView respondsToSelector:@selector(setTransparent:)]) {
+    [titlebarView setTransparent:NO];
+  }
+  if ([titlebarContainerView respondsToSelector:@selector(setTransparent:)]) {
+    [titlebarContainerView setTransparent:NO];
+  }
+
+  if (!mGeckoWindow) {
+    return;
+  }
+  mGeckoWindow->CocoaWindowDidEnterFullscreen(true);
+}
+
+- (void)windowWillExitFullScreen:(NSNotification*)notification {
+  if (!mGeckoWindow) {
+    return;
+  }
+  mGeckoWindow->CocoaWindowWillEnterFullscreen(false);
+}
+
+- (void)windowDidExitFullScreen:(NSNotification*)notification {
+  if (!mGeckoWindow) {
+    return;
+  }
+  mGeckoWindow->CocoaWindowDidEnterFullscreen(false);
+}
+
+- (void)windowDidFailToEnterFullScreen:(NSWindow*)window {
+  if (!mGeckoWindow) {
+    return;
+  }
+  mGeckoWindow->CocoaWindowDidFailFullscreen(true);
+}
+
+- (void)windowDidFailToExitFullScreen:(NSWindow*)window {
+  if (!mGeckoWindow) {
+    return;
+  }
+  mGeckoWindow->CocoaWindowDidFailFullscreen(false);
+}
+
+- (void)windowDidBecomeMain:(NSNotification*)aNotification {
+  NS_OBJC_BEGIN_TRY_IGNORE_BLOCK;
+
+  RollUpPopups();
+  ChildViewMouseTracker::ReEvaluateMouseEnterState();
+
+  // [NSApp _isRunningAppModal] will return true if we're running an OS dialog
+  // app modally. If one of those is up then we want it to retain its menu bar.
+  if ([NSApp _isRunningAppModal]) return;
+  NSWindow* window = [aNotification object];
+  if (window) [WindowDelegate paintMenubarForWindow:window];
+
+  if ([window isKindOfClass:[ToolbarWindow class]]) {
+    [(ToolbarWindow*)window windowMainStateChanged];
+  }
+
+  NS_OBJC_END_TRY_IGNORE_BLOCK;
+}
+
+- (void)windowDidResignMain:(NSNotification*)aNotification {
+  RollUpPopups();
+  ChildViewMouseTracker::ReEvaluateMouseEnterState();
+
+  // [NSApp _isRunningAppModal] will return true if we're running an OS dialog
+  // app modally. If one of those is up then we want it to retain its menu bar.
+  if ([NSApp _isRunningAppModal]) return;
+  RefPtr<nsMenuBarX> hiddenWindowMenuBar = nsMenuUtilsX::GetHiddenWindowMenuBar();
+  if (hiddenWindowMenuBar) {
+    // printf("painting hidden window menu bar due to window losing main status\n");
+    hiddenWindowMenuBar->Paint();
+  }
+
+  NSWindow* window = [aNotification object];
+  if ([window isKindOfClass:[ToolbarWindow class]]) {
+    [(ToolbarWindow*)window windowMainStateChanged];
+  }
+}
+
+- (void)windowDidBecomeKey:(NSNotification*)aNotification {
+  NS_OBJC_BEGIN_TRY_IGNORE_BLOCK;
+
+  RollUpPopups();
+  ChildViewMouseTracker::ReEvaluateMouseEnterState();
+
+  NSWindow* window = [aNotification object];
+  if ([window isSheet]) [WindowDelegate paintMenubarForWindow:window];
+
+  nsChildView* mainChildView =
+      static_cast<nsChildView*>([[(BaseWindow*)window mainChildView] widget]);
+  if (mainChildView) {
+    if (mainChildView->GetInputContext().IsPasswordEditor()) {
+      TextInputHandler::EnableSecureEventInput();
+    } else {
+      TextInputHandler::EnsureSecureEventInputDisabled();
+    }
+  }
+
+  NS_OBJC_END_TRY_IGNORE_BLOCK;
+}
+
+- (void)windowDidResignKey:(NSNotification*)aNotification {
+  NS_OBJC_BEGIN_TRY_IGNORE_BLOCK;
+
+  RollUpPopups(nsIRollupListener::AllowAnimations::No);
+
+  ChildViewMouseTracker::ReEvaluateMouseEnterState();
+
+  // If a sheet just resigned key then we should paint the menu bar
+  // for whatever window is now main.
+  NSWindow* window = [aNotification object];
+  if ([window isSheet]) [WindowDelegate paintMenubarForWindow:[NSApp mainWindow]];
+
+  TextInputHandler::EnsureSecureEventInputDisabled();
+
+  NS_OBJC_END_TRY_IGNORE_BLOCK;
+}
+
+- (void)windowWillMove:(NSNotification*)aNotification {
+  RollUpPopups();
+}
+
+- (void)windowDidMove:(NSNotification*)aNotification {
+  if (mGeckoWindow) mGeckoWindow->ReportMoveEvent();
+}
+
+- (BOOL)windowShouldClose:(id)sender {
+  nsIWidgetListener* listener = mGeckoWindow ? mGeckoWindow->GetWidgetListener() : nullptr;
+  if (listener) listener->RequestWindowClose(mGeckoWindow);
+  return NO;  // gecko will do it
+}
+
+- (void)windowWillClose:(NSNotification*)aNotification {
+  RollUpPopups();
+}
+
+- (void)windowWillMiniaturize:(NSNotification*)aNotification {
+  RollUpPopups();
+}
+
+- (void)windowDidMiniaturize:(NSNotification*)aNotification {
+  if (!mGeckoWindow) {
+    return;
+  }
+  mGeckoWindow->FinishCurrentTransitionIfMatching(nsCocoaWindow::TransitionType::Miniaturize);
+}
+
+- (void)windowDidDeminiaturize:(NSNotification*)aNotification {
+  if (!mGeckoWindow) {
+    return;
+  }
+  mGeckoWindow->FinishCurrentTransitionIfMatching(nsCocoaWindow::TransitionType::Deminiaturize);
+}
+
+- (BOOL)windowShouldZoom:(NSWindow*)window toFrame:(NSRect)proposedFrame {
+  if (!mHasEverBeenZoomed && [window isZoomed]) return NO;  // See bug 429954.
+
+  mHasEverBeenZoomed = YES;
+  return YES;
+}
+
+- (NSRect)window:(NSWindow*)window willPositionSheet:(NSWindow*)sheet usingRect:(NSRect)rect {
+  if ([window isKindOfClass:[ToolbarWindow class]]) {
+    rect.origin.y = [(ToolbarWindow*)window sheetAttachmentPosition];
+  }
+  return rect;
+}
+
+#ifdef MOZ_THUNDERBIRD
+- (void)didEndSheet:(NSWindow*)sheet returnCode:(int)returnCode contextInfo:(void*)contextInfo {
+  NS_OBJC_BEGIN_TRY_ABORT_BLOCK;
+
+  // Note: 'contextInfo' (if it is set) is the window that is the parent of
+  // the sheet.  The value of contextInfo is determined in
+  // nsCocoaWindow::Show().  If it's set, 'contextInfo' is always the top-
+  // level window, not another sheet itself.  But 'contextInfo' is nil if
+  // our parent window is also a sheet -- in that case we shouldn't send
+  // the top-level window any activate events (because it's our parent
+  // window that needs to get these events, not the top-level window).
+  [TopLevelWindowData deactivateInWindow:sheet];
+  [sheet orderOut:self];
+  if (contextInfo) [TopLevelWindowData activateInWindow:(NSWindow*)contextInfo];
+
+  NS_OBJC_END_TRY_ABORT_BLOCK;
+}
+#endif
+
+- (void)windowDidChangeBackingProperties:(NSNotification*)aNotification {
+  NS_OBJC_BEGIN_TRY_IGNORE_BLOCK;
+
+  NSWindow* window = (NSWindow*)[aNotification object];
+
+  if ([window respondsToSelector:@selector(backingScaleFactor)]) {
+    CGFloat oldFactor =
+        [[[aNotification userInfo] objectForKey:@"NSBackingPropertyOldScaleFactorKey"] doubleValue];
+    if ([window backingScaleFactor] != oldFactor) {
+      mGeckoWindow->BackingScaleFactorChanged();
+    }
+  }
+
+  NS_OBJC_END_TRY_IGNORE_BLOCK;
+}
+
+// This method is on NSWindowDelegate starting with 10.9
+- (void)windowDidChangeOcclusionState:(NSNotification*)aNotification {
+  if (mGeckoWindow) {
+    mGeckoWindow->DispatchOcclusionEvent();
+  }
+}
+
+- (nsCocoaWindow*)geckoWidget {
+  return mGeckoWindow;
+}
+
+- (bool)toplevelActiveState {
+  return mToplevelActiveState;
+}
+
+- (void)sendToplevelActivateEvents {
+  if (!mToplevelActiveState && mGeckoWindow) {
+    mGeckoWindow->CocoaSendToplevelActivateEvents();
+
+    mToplevelActiveState = true;
+  }
+}
+
+- (void)sendToplevelDeactivateEvents {
+  if (mToplevelActiveState && mGeckoWindow) {
+    mGeckoWindow->CocoaSendToplevelDeactivateEvents();
+    mToplevelActiveState = false;
+  }
+}
+
+@end
+
+@interface NSView (FrameViewMethodSwizzling)
+- (NSPoint)FrameView__closeButtonOrigin;
+- (CGFloat)FrameView__titlebarHeight;
+@end
+
+@implementation NSView (FrameViewMethodSwizzling)
+
+- (NSPoint)FrameView__closeButtonOrigin {
+  if (![self.window isKindOfClass:[ToolbarWindow class]]) {
+    return self.FrameView__closeButtonOrigin;
+  }
+  ToolbarWindow* win = (ToolbarWindow*)[self window];
+  if (win.drawsContentsIntoWindowFrame && !(win.styleMask & NSWindowStyleMaskFullScreen) &&
+      (win.styleMask & NSWindowStyleMaskTitled)) {
+    const NSRect buttonsRect = win.windowButtonsRect;
+    if (NSIsEmptyRect(buttonsRect)) {
+      // Empty rect. Let's hide the buttons.
+      // Position is in non-flipped window coordinates. Using frame's height
+      // for the vertical coordinate will move the buttons above the window,
+      // making them invisible.
+      return NSMakePoint(buttonsRect.origin.x, win.frame.size.height);
+    } else if (win.windowTitlebarLayoutDirection == NSUserInterfaceLayoutDirectionRightToLeft) {
+      // We're in RTL mode, which means that the close button is the rightmost
+      // button of the three window buttons. and buttonsRect.origin is the
+      // bottom left corner of the green (zoom) button. The close button is 40px
+      // to the right of the zoom button. This is confirmed to be the same on
+      // all macOS versions between 10.12 - 12.0.
+      return NSMakePoint(buttonsRect.origin.x + 40.0f, buttonsRect.origin.y);
+    }
+    return buttonsRect.origin;
+  }
+  return self.FrameView__closeButtonOrigin;
+}
+
+- (CGFloat)FrameView__titlebarHeight {
+  CGFloat height = [self FrameView__titlebarHeight];
+  if ([[self window] isKindOfClass:[ToolbarWindow class]]) {
+    // Make sure that the titlebar height includes our shifted buttons.
+    // The following coordinates are in window space, with the origin being at the bottom left
+    // corner of the window.
+    ToolbarWindow* win = (ToolbarWindow*)[self window];
+    CGFloat frameHeight = [self frame].size.height;
+    CGFloat windowButtonY = frameHeight;
+    if (!NSIsEmptyRect(win.windowButtonsRect) && win.drawsContentsIntoWindowFrame &&
+        !(win.styleMask & NSWindowStyleMaskFullScreen) &&
+        (win.styleMask & NSWindowStyleMaskTitled)) {
+      windowButtonY = win.windowButtonsRect.origin.y;
+    }
+    height = std::max(height, frameHeight - windowButtonY);
+  }
+  return height;
+}
+
+@end
+
+static NSMutableSet* gSwizzledFrameViewClasses = nil;
+
+@interface NSWindow (PrivateSetNeedsDisplayInRectMethod)
+- (void)_setNeedsDisplayInRect:(NSRect)aRect;
+@end
+
+@interface NSView (NSVisualEffectViewSetMaskImage)
+- (void)setMaskImage:(NSImage*)image;
+@end
+
+@interface BaseWindow (Private)
+- (void)removeTrackingArea;
+- (void)cursorUpdated:(NSEvent*)aEvent;
+- (void)reflowTitlebarElements;
+@end
+
+@implementation BaseWindow
+
+// The frame of a window is implemented using undocumented NSView subclasses.
+// We offset the window buttons by overriding the method _closeButtonOrigin on
+// these frame view classes. The class which is
+// used for a window is determined in the window's frameViewClassForStyleMask:
+// method, so this is where we make sure that we have swizzled the method on
+// all encountered classes.
++ (Class)frameViewClassForStyleMask:(NSUInteger)styleMask {
+  Class frameViewClass = [super frameViewClassForStyleMask:styleMask];
+
+  if (!gSwizzledFrameViewClasses) {
+    gSwizzledFrameViewClasses = [[NSMutableSet setWithCapacity:3] retain];
+    if (!gSwizzledFrameViewClasses) {
+      return frameViewClass;
+    }
+  }
+
+  static IMP our_closeButtonOrigin =
+      class_getMethodImplementation([NSView class], @selector(FrameView__closeButtonOrigin));
+  static IMP our_titlebarHeight =
+      class_getMethodImplementation([NSView class], @selector(FrameView__titlebarHeight));
+
+  if (![gSwizzledFrameViewClasses containsObject:frameViewClass]) {
+    // Either of these methods might be implemented in both a subclass of
+    // NSFrameView and one of its own subclasses.  Which means that if we
+    // aren't careful we might end up swizzling the same method twice.
+    // Since method swizzling involves swapping pointers, this would break
+    // things.
+    IMP _closeButtonOrigin =
+        class_getMethodImplementation(frameViewClass, @selector(_closeButtonOrigin));
+    if (_closeButtonOrigin && _closeButtonOrigin != our_closeButtonOrigin) {
+      nsToolkit::SwizzleMethods(frameViewClass, @selector(_closeButtonOrigin),
+                                @selector(FrameView__closeButtonOrigin));
+    }
+
+    // Override _titlebarHeight so that the floating titlebar doesn't clip the bottom of the
+    // window buttons which we move down with our override of _closeButtonOrigin.
+    IMP _titlebarHeight = class_getMethodImplementation(frameViewClass, @selector(_titlebarHeight));
+    if (_titlebarHeight && _titlebarHeight != our_titlebarHeight) {
+      nsToolkit::SwizzleMethods(frameViewClass, @selector(_titlebarHeight),
+                                @selector(FrameView__titlebarHeight));
+    }
+
+    [gSwizzledFrameViewClasses addObject:frameViewClass];
+  }
+
+  return frameViewClass;
+}
+
+- (id)initWithContentRect:(NSRect)aContentRect
+                styleMask:(NSUInteger)aStyle
+                  backing:(NSBackingStoreType)aBufferingType
+                    defer:(BOOL)aFlag {
+  mDrawsIntoWindowFrame = NO;
+  [super initWithContentRect:aContentRect styleMask:aStyle backing:aBufferingType defer:aFlag];
+  mState = nil;
+  mDisabledNeedsDisplay = NO;
+  mTrackingArea = nil;
+  mDirtyRect = NSZeroRect;
+  mBeingShown = NO;
+  mDrawTitle = NO;
+  mUseMenuStyle = NO;
+  mTouchBar = nil;
+  mIsAnimationSuppressed = NO;
+  [self updateTrackingArea];
+
+  return self;
+}
+
+// Returns an autoreleased NSImage.
+static NSImage* GetMenuMaskImage() {
+  CGFloat radius = 4.0f;
+  NSEdgeInsets insets = {5, 5, 5, 5};
+  NSSize maskSize = {12, 12};
+  NSImage* maskImage = [NSImage imageWithSize:maskSize
+                                      flipped:YES
+                               drawingHandler:^BOOL(NSRect dstRect) {
+                                 NSBezierPath* path =
+                                     [NSBezierPath bezierPathWithRoundedRect:dstRect
+                                                                     xRadius:radius
+                                                                     yRadius:radius];
+                                 [[NSColor colorWithDeviceWhite:1.0 alpha:1.0] set];
+                                 [path fill];
+                                 return YES;
+                               }];
+  [maskImage setCapInsets:insets];
+  return maskImage;
+}
+
+- (void)swapOutChildViewWrapper:(NSView*)aNewWrapper {
+  [aNewWrapper setFrame:[[self contentView] frame]];
+  NSView* childView = [[self mainChildView] retain];
+  [childView removeFromSuperview];
+  [aNewWrapper addSubview:childView];
+  [childView release];
+  [super setContentView:aNewWrapper];
+}
+
+- (void)setUseMenuStyle:(BOOL)aValue {
+  if (aValue && !mUseMenuStyle) {
+    // Turn on rounded corner masking.
+    NSView* effectView = VibrancyManager::CreateEffectView(VibrancyType::MENU, YES);
+    [effectView setMaskImage:GetMenuMaskImage()];
+    [self swapOutChildViewWrapper:effectView];
+    [effectView release];
+  } else if (mUseMenuStyle && !aValue) {
+    // Turn off rounded corner masking.
+    NSView* wrapper = [[NSView alloc] initWithFrame:NSZeroRect];
+    [wrapper setWantsLayer:YES];
+    [self swapOutChildViewWrapper:wrapper];
+    [wrapper release];
+  }
+  mUseMenuStyle = aValue;
+}
+
+- (NSTouchBar*)makeTouchBar {
+  mTouchBar = [[nsTouchBar alloc] init];
+  if (mTouchBar) {
+    sTouchBarIsInitialized = YES;
+  }
+  return mTouchBar;
+}
+
+- (void)setBeingShown:(BOOL)aValue {
+  mBeingShown = aValue;
+}
+
+- (BOOL)isBeingShown {
+  return mBeingShown;
+}
+
+- (BOOL)isVisibleOrBeingShown {
+  return [super isVisible] || mBeingShown;
+}
+
+- (void)setIsAnimationSuppressed:(BOOL)aValue {
+  mIsAnimationSuppressed = aValue;
+}
+
+- (BOOL)isAnimationSuppressed {
+  return mIsAnimationSuppressed;
+}
+
+- (void)disableSetNeedsDisplay {
+  mDisabledNeedsDisplay = YES;
+}
+
+- (void)enableSetNeedsDisplay {
+  mDisabledNeedsDisplay = NO;
+}
+
+- (void)dealloc {
+  [mTouchBar release];
+  [self removeTrackingArea];
+  ChildViewMouseTracker::OnDestroyWindow(self);
+  [super dealloc];
+}
+
+static const NSString* kStateTitleKey = @"title";
+static const NSString* kStateDrawsContentsIntoWindowFrameKey = @"drawsContentsIntoWindowFrame";
+static const NSString* kStateShowsToolbarButton = @"showsToolbarButton";
+static const NSString* kStateCollectionBehavior = @"collectionBehavior";
+static const NSString* kStateWantsTitleDrawn = @"wantsTitleDrawn";
+
+- (void)importState:(NSDictionary*)aState {
+  if (NSString* title = [aState objectForKey:kStateTitleKey]) {
+    [self setTitle:title];
+  }
+  [self setDrawsContentsIntoWindowFrame:[[aState objectForKey:kStateDrawsContentsIntoWindowFrameKey]
+                                            boolValue]];
+  [self setShowsToolbarButton:[[aState objectForKey:kStateShowsToolbarButton] boolValue]];
+  [self setCollectionBehavior:[[aState objectForKey:kStateCollectionBehavior] unsignedIntValue]];
+  [self setWantsTitleDrawn:[[aState objectForKey:kStateWantsTitleDrawn] boolValue]];
+}
+
+- (NSMutableDictionary*)exportState {
+  NSMutableDictionary* state = [NSMutableDictionary dictionaryWithCapacity:10];
+  if (NSString* title = [self title]) {
+    [state setObject:title forKey:kStateTitleKey];
+  }
+  [state setObject:[NSNumber numberWithBool:[self drawsContentsIntoWindowFrame]]
+            forKey:kStateDrawsContentsIntoWindowFrameKey];
+  [state setObject:[NSNumber numberWithBool:[self showsToolbarButton]]
+            forKey:kStateShowsToolbarButton];
+  [state setObject:[NSNumber numberWithUnsignedInt:[self collectionBehavior]]
+            forKey:kStateCollectionBehavior];
+  [state setObject:[NSNumber numberWithBool:[self wantsTitleDrawn]] forKey:kStateWantsTitleDrawn];
+  return state;
+}
+
+- (void)setDrawsContentsIntoWindowFrame:(BOOL)aState {
+  bool changed = (aState != mDrawsIntoWindowFrame);
+  mDrawsIntoWindowFrame = aState;
+  if (changed) {
+    [self reflowTitlebarElements];
+  }
+}
+
+- (BOOL)drawsContentsIntoWindowFrame {
+  return mDrawsIntoWindowFrame;
+}
+
+- (NSRect)childViewRectForFrameRect:(NSRect)aFrameRect {
+  if (mDrawsIntoWindowFrame) {
+    return aFrameRect;
+  }
+  NSUInteger styleMask = [self styleMask];
+  styleMask &= ~NSWindowStyleMaskFullSizeContentView;
+  return [NSWindow contentRectForFrameRect:aFrameRect styleMask:styleMask];
+}
+
+- (NSRect)frameRectForChildViewRect:(NSRect)aChildViewRect {
+  if (mDrawsIntoWindowFrame) {
+    return aChildViewRect;
+  }
+  NSUInteger styleMask = [self styleMask];
+  styleMask &= ~NSWindowStyleMaskFullSizeContentView;
+  return [NSWindow frameRectForContentRect:aChildViewRect styleMask:styleMask];
+}
+
+- (NSTimeInterval)animationResizeTime:(NSRect)newFrame {
+  if (mIsAnimationSuppressed) {
+    // Should not animate the initial session-restore size change
+    return 0.0;
+  }
+
+  return [super animationResizeTime:newFrame];
+}
+
+- (void)setWantsTitleDrawn:(BOOL)aDrawTitle {
+  mDrawTitle = aDrawTitle;
+  [self setTitleVisibility:mDrawTitle ? NSWindowTitleVisible : NSWindowTitleHidden];
+}
+
+- (BOOL)wantsTitleDrawn {
+  return mDrawTitle;
+}
+
+- (NSView*)trackingAreaView {
+  NSView* contentView = [self contentView];
+  return [contentView superview] ? [contentView superview] : contentView;
+}
+
+- (NSArray<NSView*>*)contentViewContents {
+  return [[[[self contentView] subviews] copy] autorelease];
+}
+
+- (ChildView*)mainChildView {
+  NSView* contentView = [self contentView];
+  NSView* lastView = [[contentView subviews] lastObject];
+  if ([lastView isKindOfClass:[ChildView class]]) {
+    return (ChildView*)lastView;
+  }
+  return nil;
+}
+
+- (void)removeTrackingArea {
+  if (mTrackingArea) {
+    [[self trackingAreaView] removeTrackingArea:mTrackingArea];
+    [mTrackingArea release];
+    mTrackingArea = nil;
+  }
+}
+
+- (void)updateTrackingArea {
+  [self removeTrackingArea];
+
+  NSView* view = [self trackingAreaView];
+  const NSTrackingAreaOptions options =
+      NSTrackingMouseEnteredAndExited | NSTrackingMouseMoved | NSTrackingActiveAlways;
+  mTrackingArea = [[NSTrackingArea alloc] initWithRect:[view bounds]
+                                               options:options
+                                                 owner:self
+                                              userInfo:nil];
+  [view addTrackingArea:mTrackingArea];
+}
+
+- (void)mouseEntered:(NSEvent*)aEvent {
+  ChildViewMouseTracker::MouseEnteredWindow(aEvent);
+}
+
+- (void)mouseExited:(NSEvent*)aEvent {
+  ChildViewMouseTracker::MouseExitedWindow(aEvent);
+}
+
+- (void)mouseMoved:(NSEvent*)aEvent {
+  ChildViewMouseTracker::MouseMoved(aEvent);
+}
+
+- (void)cursorUpdated:(NSEvent*)aEvent {
+  // Nothing to do here, but NSTrackingArea wants us to implement this method.
+}
+
+- (void)_setNeedsDisplayInRect:(NSRect)aRect {
+  // Prevent unnecessary invalidations due to moving NSViews (e.g. for plugins)
+  if (!mDisabledNeedsDisplay) {
+    // This method is only called by Cocoa, so when we're here, we know that
+    // it's available and don't need to check whether our superclass responds
+    // to the selector.
+    [super _setNeedsDisplayInRect:aRect];
+    mDirtyRect = NSUnionRect(mDirtyRect, aRect);
+  }
+}
+
+- (NSRect)getAndResetNativeDirtyRect {
+  NSRect dirtyRect = mDirtyRect;
+  mDirtyRect = NSZeroRect;
+  return dirtyRect;
+}
+
+// Possibly move the titlebar buttons.
+- (void)reflowTitlebarElements {
+  NSView* frameView = [[self contentView] superview];
+  if ([frameView respondsToSelector:@selector(_tileTitlebarAndRedisplay:)]) {
+    [frameView _tileTitlebarAndRedisplay:NO];
+  }
+}
+
+- (BOOL)respondsToSelector:(SEL)aSelector {
+  // Claim the window doesn't respond to this so that the system
+  // doesn't steal keyboard equivalents for it. Bug 613710.
+  if (aSelector == @selector(cancelOperation:)) {
+    return NO;
+  }
+
+  return [super respondsToSelector:aSelector];
+}
+
+- (void)doCommandBySelector:(SEL)aSelector {
+  // We override this so that it won't beep if it can't act.
+  // We want to control the beeping for missing or disabled
+  // commands ourselves.
+  [self tryToPerform:aSelector with:nil];
+}
+
+- (id)accessibilityAttributeValue:(NSString*)attribute {
+  NS_OBJC_BEGIN_TRY_BLOCK_RETURN;
+
+  id retval = [super accessibilityAttributeValue:attribute];
+
+  // The following works around a problem with Text-to-Speech on OS X 10.7.
+  // See bug 674612 for more info.
+  //
+  // When accessibility is off, AXUIElementCopyAttributeValue(), when called
+  // on an AXApplication object to get its AXFocusedUIElement attribute,
+  // always returns an AXWindow object (the actual browser window -- never a
+  // mozAccessible object).  This also happens with accessibility turned on,
+  // if no other object in the browser window has yet been focused.  But if
+  // the browser window has a title bar (as it currently always does), the
+  // AXWindow object will always have four "accessible" children, one of which
+  // is an AXStaticText object (the title bar's "title"; the other three are
+  // the close, minimize and zoom buttons).  This means that (for complicated
+  // reasons, for which see bug 674612) Text-to-Speech on OS X 10.7 will often
+  // "speak" the window title, no matter what text is selected, or even if no
+  // text at all is selected.  (This always happens when accessibility is off.
+  // It doesn't happen in Firefox releases because Apple has (on OS X 10.7)
+  // special-cased the handling of apps whose CFBundleIdentifier is
+  // org.mozilla.firefox.)
+  //
+  // We work around this problem by only returning AXChildren that are
+  // mozAccessible object or are one of the titlebar's buttons (which
+  // instantiate subclasses of NSButtonCell).
+  if ([retval isKindOfClass:[NSArray class]] && [attribute isEqualToString:@"AXChildren"]) {
+    NSMutableArray* holder = [NSMutableArray arrayWithCapacity:10];
+    [holder addObjectsFromArray:(NSArray*)retval];
+    NSUInteger count = [holder count];
+    for (NSInteger i = count - 1; i >= 0; --i) {
+      id item = [holder objectAtIndex:i];
+      // Remove anything from holder that isn't one of the titlebar's buttons
+      // (which instantiate subclasses of NSButtonCell) or a mozAccessible
+      // object (or one of its subclasses).
+      if (![item isKindOfClass:[NSButtonCell class]] &&
+          ![item respondsToSelector:@selector(hasRepresentedView)]) {
+        [holder removeObjectAtIndex:i];
+      }
+    }
+    retval = [NSArray arrayWithArray:holder];
+  }
+
+  return retval;
+
+  NS_OBJC_END_TRY_BLOCK_RETURN(nil);
+}
+
+- (void)releaseJSObjects {
+  [mTouchBar releaseJSObjects];
+}
+
+@end
+
+@interface NSView (NSThemeFrame)
+- (void)_drawTitleStringInClip:(NSRect)aRect;
+- (void)_maskCorners:(NSUInteger)aFlags clipRect:(NSRect)aRect;
+@end
+
+@implementation MOZTitlebarView
+
+- (instancetype)initWithFrame:(NSRect)aFrame {
+  self = [super initWithFrame:aFrame];
+
+  self.material = NSVisualEffectMaterialTitlebar;
+  self.blendingMode = NSVisualEffectBlendingModeWithinWindow;
+
+  // Add a separator line at the bottom of the titlebar. NSBoxSeparator isn't a perfect match for
+  // a native titlebar separator, but it's better than nothing.
+  // We really want the appearance that _NSTitlebarDecorationView creates with the help of CoreUI,
+  // but there's no public API for that.
+  NSBox* separatorLine = [[NSBox alloc] initWithFrame:NSMakeRect(0, 0, aFrame.size.width, 1)];
+  separatorLine.autoresizingMask = NSViewWidthSizable | NSViewMaxYMargin;
+  separatorLine.boxType = NSBoxSeparator;
+  [self addSubview:separatorLine];
+  [separatorLine release];
+
+  return self;
+}
+
+- (BOOL)mouseDownCanMoveWindow {
+  return YES;
+}
+
+- (void)mouseUp:(NSEvent*)event {
+  if ([event clickCount] == 2) {
+    // Handle titlebar double click. We don't get the window's default behavior here because the
+    // window uses NSWindowStyleMaskFullSizeContentView, and this view (the titlebar gradient view)
+    // is technically part of the window "contents" (it's a subview of the content view).
+    if (nsCocoaUtils::ShouldZoomOnTitlebarDoubleClick()) {
+      [[self window] performZoom:nil];
+    } else if (nsCocoaUtils::ShouldMinimizeOnTitlebarDoubleClick()) {
+      [[self window] performMiniaturize:nil];
+    }
+  }
+}
+
+@end
+
+@interface MOZTitlebarAccessoryView : NSView
+@end
+
+@implementation MOZTitlebarAccessoryView : NSView
+- (void)viewWillMoveToWindow:(NSWindow*)aWindow {
+  if (aWindow) {
+    // When entering full screen mode, titlebar accessory views are inserted
+    // into a floating NSWindow which houses the window titlebar and toolbars.
+    // In order to work around a drawing bug with titlebarAppearsTransparent
+    // windows in full screen mode, disable titlebar separators for all
+    // NSWindows that this view is used in, including the floating full screen
+    // toolbar window. The drawing bug was filed as FB9056136. See bug 1700211
+    // for more details.
+#if !defined(MAC_OS_VERSION_11_0) || MAC_OS_X_VERSION_MAX_ALLOWED < MAC_OS_VERSION_11_0
+    if (nsCocoaFeatures::OnBigSurOrLater()) {
+#else
+    if (@available(macOS 11.0, *)) {
+#endif
+      aWindow.titlebarSeparatorStyle = NSTitlebarSeparatorStyleNone;
+    }
+  }
+}
+@end
+
+@implementation FullscreenTitlebarTracker
+- (FullscreenTitlebarTracker*)init {
+  [super init];
+  self.view = [[[MOZTitlebarAccessoryView alloc] initWithFrame:NSZeroRect] autorelease];
+  self.hidden = YES;
+  return self;
+}
+@end
+
+// This class allows us to exercise control over the window's title bar. It is
+// used for all windows with titlebars.
+//
+// ToolbarWindow supports two modes:
+//  - drawsContentsIntoWindowFrame mode: In this mode, the Gecko ChildView is
+//    sized to cover the entire window frame and manages titlebar drawing.
+//  - separate titlebar mode, with support for unified toolbars: In this mode,
+//    the Gecko ChildView does not extend into the titlebar. However, this
+//    window's content view (which is the ChildView's superview) *does* extend
+//    into the titlebar. Moreover, in this mode, we place a MOZTitlebarView
+//    in the content view, as a sibling of the ChildView.
+//
+// The "separate titlebar mode" supports the "unified toolbar" look:
+// If there's a toolbar right below the titlebar, the two can "connect" and
+// form a single gradient without a separator line in between.
+//
+// The following mechanism communicates the height of the unified toolbar to
+// the ToolbarWindow:
+//
+// 1) In the style sheet we set the toolbar's -moz-appearance to toolbar.
+// 2) When the toolbar is visible and we paint the application chrome
+//    window, the array that Gecko passes nsChildView::UpdateThemeGeometries
+//    will contain an entry for the widget type StyleAppearance::Toolbar.
+// 3) nsChildView::UpdateThemeGeometries passes the toolbar's height, plus the
+//    titlebar height, to -[ToolbarWindow setUnifiedToolbarHeight:].
+//
+// The actual drawing of the gradient happens in two parts: The titlebar part
+// (i.e. the top 22 pixels of the gradient) is drawn by the MOZTitlebarView,
+// which is a subview of the window's content view and a sibling of the ChildView.
+// The rest of the gradient is drawn by Gecko into the ChildView, as part of the
+// -moz-appearance rendering of the toolbar.
+@implementation ToolbarWindow
+
+- (id)initWithContentRect:(NSRect)aChildViewRect
+                styleMask:(NSUInteger)aStyle
+                  backing:(NSBackingStoreType)aBufferingType
+                    defer:(BOOL)aFlag {
+  NS_OBJC_BEGIN_TRY_BLOCK_RETURN;
+
+  // We treat aChildViewRect as the rectangle that the window's main ChildView
+  // should be sized to. Get the right frameRect for the requested child view
+  // rect.
+  NSRect frameRect = [NSWindow frameRectForContentRect:aChildViewRect styleMask:aStyle];
+
+  // Always size the content view to the full frame size of the window.
+  // We do this even if we want this window to have a titlebar; in that case, the window's content
+  // view covers the entire window but the ChildView inside it will only cover the content area. We
+  // do this so that we can render the titlebar gradient manually, with a subview of our content
+  // view that's positioned in the titlebar area. This lets us have a smooth connection between
+  // titlebar and toolbar gradient in case the window has a "unified toolbar + titlebar" look.
+  // Moreover, always using a full size content view lets us toggle the titlebar on and off without
+  // changing the window's style mask (which would have other subtle effects, for example on
+  // keyboard focus).
+  aStyle |= NSWindowStyleMaskFullSizeContentView;
+
+  // -[NSWindow initWithContentRect:styleMask:backing:defer:] calls
+  // [self frameRectForContentRect:styleMask:] to convert the supplied content
+  // rect to the window's frame rect. We've overridden that method to be a
+  // pass-through function. So, in order to get the intended frameRect, we need
+  // to supply frameRect itself as the "content rect".
+  NSRect contentRect = frameRect;
+
+  if ((self = [super initWithContentRect:contentRect
+                               styleMask:aStyle
+                                 backing:aBufferingType
+                                   defer:aFlag])) {
+    mTitlebarView = nil;
+    mUnifiedToolbarHeight = 22.0f;
+    mSheetAttachmentPosition = aChildViewRect.size.height;
+    mWindowButtonsRect = NSZeroRect;
+    mInitialTitlebarHeight = [self titlebarHeight];
+
+    [self setTitlebarAppearsTransparent:YES];
+#if !defined(MAC_OS_VERSION_11_0) || MAC_OS_X_VERSION_MAX_ALLOWED < MAC_OS_VERSION_11_0
+    if (nsCocoaFeatures::OnBigSurOrLater()) {
+#else
+    if (@available(macOS 11.0, *)) {
+#endif
+      self.titlebarSeparatorStyle = NSTitlebarSeparatorStyleNone;
+    }
+    [self updateTitlebarView];
+
+    mFullscreenTitlebarTracker = [[FullscreenTitlebarTracker alloc] init];
+    // revealAmount is an undocumented property of
+    // NSTitlebarAccessoryViewController that updates whenever the menubar
+    // slides down in fullscreen mode.
+    [mFullscreenTitlebarTracker addObserver:self
+                                 forKeyPath:@"revealAmount"
+                                    options:NSKeyValueObservingOptionNew
+                                    context:nil];
+    // Adding this accessory view controller allows us to shift the toolbar down
+    // when the user mouses to the top of the screen in fullscreen.
+    [(NSWindow*)self addTitlebarAccessoryViewController:mFullscreenTitlebarTracker];
+  }
+  return self;
+
+  NS_OBJC_END_TRY_BLOCK_RETURN(nil);
+}
+
+- (void)observeValueForKeyPath:(NSString*)keyPath
+                      ofObject:(id)object
+                        change:(NSDictionary<NSKeyValueChangeKey, id>*)change
+                       context:(void*)context {
+  if ([keyPath isEqualToString:@"revealAmount"]) {
+    [[self mainChildView] ensureNextCompositeIsAtomicWithMainThreadPaint];
+    NSNumber* revealAmount = (change[NSKeyValueChangeNewKey]);
+    [self updateTitlebarShownAmount:[revealAmount doubleValue]];
+  } else {
+    [super observeValueForKeyPath:keyPath ofObject:object change:change context:context];
+  }
+}
+
+static bool ScreenHasNotch(nsCocoaWindow* aGeckoWindow) {
+  if (@available(macOS 12.0, *)) {
+    nsCOMPtr<nsIScreen> widgetScreen = aGeckoWindow->GetWidgetScreen();
+    NSScreen* cocoaScreen = ScreenHelperCocoa::CocoaScreenForScreen(widgetScreen);
+    return cocoaScreen.safeAreaInsets.top != 0.0f;
+  }
+  return false;
+}
+
+static bool ShouldShiftByMenubarHeightInFullscreen(nsCocoaWindow* aWindow) {
+  switch (StaticPrefs::widget_macos_shift_by_menubar_on_fullscreen()) {
+    case 0:
+      return false;
+    case 1:
+      return true;
+    default:
+      break;
+  }
+  // TODO: On notch-less macbooks, this creates extra space when the
+  // "automatically show and hide the menubar on fullscreen" option is unchecked
+  // (default checked). We tried to detect that in bug 1737831 but it wasn't
+  // reliable enough, see the regressions from that bug. For now, stick to the
+  // good behavior for default configurations (that is, shift by menubar height
+  // on notch-less macbooks, and don't for devices that have a notch). This will
+  // need refinement in the future.
+  return !ScreenHasNotch(aWindow);
+}
+
+- (void)updateTitlebarShownAmount:(CGFloat)aShownAmount {
+  NSInteger styleMask = [self styleMask];
+  if (!(styleMask & NSWindowStyleMaskFullScreen)) {
+    // We are not interested in the size of the titlebar unless we are in
+    // fullscreen.
+    return;
+  }
+
+  // [NSApp mainMenu] menuBarHeight] returns one of two values: the full height
+  // if the menubar is shown or is in the process of being shown, and 0
+  // otherwise. Since we are multiplying the menubar height by aShownAmount, we
+  // always want the full height.
+  CGFloat menuBarHeight = NSApp.mainMenu.menuBarHeight;
+  if (menuBarHeight > 0.0f) {
+    mMenuBarHeight = menuBarHeight;
+  }
+  if ([[self delegate] isKindOfClass:[WindowDelegate class]]) {
+    WindowDelegate* windowDelegate = (WindowDelegate*)[self delegate];
+    nsCocoaWindow* geckoWindow = [windowDelegate geckoWidget];
+    if (!geckoWindow) {
+      return;
+    }
+
+    if (nsIWidgetListener* listener = geckoWindow->GetWidgetListener()) {
+      // Use the titlebar height cached in our frame rather than
+      // [ToolbarWindow titlebarHeight]. titlebarHeight returns 0 when we're in
+      // fullscreen.
+      CGFloat shiftByPixels = mInitialTitlebarHeight * aShownAmount;
+      if (ShouldShiftByMenubarHeightInFullscreen(geckoWindow)) {
+        shiftByPixels += mMenuBarHeight * aShownAmount;
+      }
+      // Use mozilla::DesktopToLayoutDeviceScale rather than the
+      // DesktopToLayoutDeviceScale in nsCocoaWindow. The latter accounts for
+      // screen DPI. We don't want that because the revealAmount property
+      // already accounts for it, so we'd be compounding DPI scales > 1.
+      mozilla::DesktopCoord coord =
+          LayoutDeviceCoord(shiftByPixels) / mozilla::DesktopToLayoutDeviceScale();
+
+      listener->MacFullscreenMenubarOverlapChanged(coord);
+    }
+  }
+}
+
+- (void)dealloc {
+  [mTitlebarView release];
+  [mFullscreenTitlebarTracker removeObserver:self forKeyPath:@"revealAmount"];
+  [mFullscreenTitlebarTracker removeFromParentViewController];
+  [mFullscreenTitlebarTracker release];
+
+  [super dealloc];
+}
+
+- (NSArray<NSView*>*)contentViewContents {
+  NSMutableArray<NSView*>* contents = [[[self contentView] subviews] mutableCopy];
+  if (mTitlebarView) {
+    // Do not include the titlebar gradient view in the returned array.
+    [contents removeObject:mTitlebarView];
+  }
+  return [contents autorelease];
+}
+
+- (void)updateTitlebarView {
+  BOOL needTitlebarView = ![self drawsContentsIntoWindowFrame] || mUnifiedToolbarHeight > 0;
+  if (needTitlebarView && !mTitlebarView) {
+    mTitlebarView = [[MOZTitlebarView alloc] initWithFrame:[self unifiedToolbarRect]];
+    mTitlebarView.autoresizingMask = NSViewWidthSizable | NSViewMinYMargin;
+    [self.contentView addSubview:mTitlebarView positioned:NSWindowBelow relativeTo:nil];
+  } else if (needTitlebarView && mTitlebarView) {
+    mTitlebarView.frame = [self unifiedToolbarRect];
+  } else if (!needTitlebarView && mTitlebarView) {
+    [mTitlebarView removeFromSuperview];
+    [mTitlebarView release];
+    mTitlebarView = nil;
+  }
+}
+
+- (void)windowMainStateChanged {
+  [self setTitlebarNeedsDisplay];
+  [[self mainChildView] ensureNextCompositeIsAtomicWithMainThreadPaint];
+}
+
+- (void)setTitlebarNeedsDisplay {
+  [mTitlebarView setNeedsDisplay:YES];
+}
+
+- (NSRect)titlebarRect {
+  CGFloat titlebarHeight = [self titlebarHeight];
+  return NSMakeRect(0, [self frame].size.height - titlebarHeight, [self frame].size.width,
+                    titlebarHeight);
+}
+
+// In window contentView coordinates (origin bottom left)
+- (NSRect)unifiedToolbarRect {
+  return NSMakeRect(0, [self frame].size.height - mUnifiedToolbarHeight, [self frame].size.width,
+                    mUnifiedToolbarHeight);
+}
+
+// Returns the unified height of titlebar + toolbar.
+- (CGFloat)unifiedToolbarHeight {
+  return mUnifiedToolbarHeight;
+}
+
+- (CGFloat)titlebarHeight {
+  // We use the original content rect here, not what we return from
+  // [self contentRectForFrameRect:], because that would give us a
+  // titlebarHeight of zero.
+  NSRect frameRect = [self frame];
+  NSUInteger styleMask = [self styleMask];
+  styleMask &= ~NSWindowStyleMaskFullSizeContentView;
+  NSRect originalContentRect = [NSWindow contentRectForFrameRect:frameRect styleMask:styleMask];
+  return NSMaxY(frameRect) - NSMaxY(originalContentRect);
+}
+
+// Stores the complete height of titlebar + toolbar.
+- (void)setUnifiedToolbarHeight:(CGFloat)aHeight {
+  if (aHeight == mUnifiedToolbarHeight) return;
+
+  mUnifiedToolbarHeight = aHeight;
+
+  [self updateTitlebarView];
+}
+
+// Extending the content area into the title bar works by resizing the
+// mainChildView so that it covers the titlebar.
+- (void)setDrawsContentsIntoWindowFrame:(BOOL)aState {
+  BOOL stateChanged = ([self drawsContentsIntoWindowFrame] != aState);
+  [super setDrawsContentsIntoWindowFrame:aState];
+  if (stateChanged && [[self delegate] isKindOfClass:[WindowDelegate class]]) {
+    // Here we extend / shrink our mainChildView. We do that by firing a resize
+    // event which will cause the ChildView to be resized to the rect returned
+    // by nsCocoaWindow::GetClientBounds. GetClientBounds bases its return
+    // value on what we return from drawsContentsIntoWindowFrame.
+    WindowDelegate* windowDelegate = (WindowDelegate*)[self delegate];
+    nsCocoaWindow* geckoWindow = [windowDelegate geckoWidget];
+    if (geckoWindow) {
+      // Re-layout our contents.
+      geckoWindow->ReportSizeEvent();
+    }
+
+    // Resizing the content area causes a reflow which would send a synthesized
+    // mousemove event to the old mouse position relative to the top left
+    // corner of the content area. But the mouse has shifted relative to the
+    // content area, so that event would have wrong position information. So
+    // we'll send a mouse move event with the correct new position.
+    ChildViewMouseTracker::ResendLastMouseMoveEvent();
+  }
+
+  [self updateTitlebarView];
+}
+
+- (void)setWantsTitleDrawn:(BOOL)aDrawTitle {
+  [super setWantsTitleDrawn:aDrawTitle];
+  [self setTitlebarNeedsDisplay];
+}
+
+- (void)setSheetAttachmentPosition:(CGFloat)aY {
+  mSheetAttachmentPosition = aY;
+}
+
+- (CGFloat)sheetAttachmentPosition {
+  return mSheetAttachmentPosition;
+}
+
+- (void)placeWindowButtons:(NSRect)aRect {
+  if (!NSEqualRects(mWindowButtonsRect, aRect)) {
+    mWindowButtonsRect = aRect;
+    [self reflowTitlebarElements];
+  }
+}
+
+- (NSRect)windowButtonsRect {
+  return mWindowButtonsRect;
+}
+
+// Returning YES here makes the setShowsToolbarButton method work even though
+// the window doesn't contain an NSToolbar.
+- (BOOL)_hasToolbar {
+  return YES;
+}
+
+// Dispatch a toolbar pill button clicked message to Gecko.
+- (void)_toolbarPillButtonClicked:(id)sender {
+  NS_OBJC_BEGIN_TRY_IGNORE_BLOCK;
+
+  RollUpPopups();
+
+  if ([[self delegate] isKindOfClass:[WindowDelegate class]]) {
+    WindowDelegate* windowDelegate = (WindowDelegate*)[self delegate];
+    nsCocoaWindow* geckoWindow = [windowDelegate geckoWidget];
+    if (!geckoWindow) return;
+
+    nsIWidgetListener* listener = geckoWindow->GetWidgetListener();
+    if (listener) listener->OSToolbarButtonPressed();
+  }
+
+  NS_OBJC_END_TRY_IGNORE_BLOCK;
+}
+
+// Retain and release "self" to avoid crashes when our widget (and its native
+// window) is closed as a result of processing a key equivalent (e.g.
+// Command+w or Command+q).  This workaround is only needed for a window
+// that can become key.
+- (BOOL)performKeyEquivalent:(NSEvent*)theEvent {
+  NS_OBJC_BEGIN_TRY_BLOCK_RETURN;
+
+  NSWindow* nativeWindow = [self retain];
+  BOOL retval = [super performKeyEquivalent:theEvent];
+  [nativeWindow release];
+  return retval;
+
+  NS_OBJC_END_TRY_BLOCK_RETURN(NO);
+}
+
+- (void)sendEvent:(NSEvent*)anEvent {
+  NSEventType type = [anEvent type];
+
+  switch (type) {
+    case NSEventTypeScrollWheel:
+    case NSEventTypeLeftMouseDown:
+    case NSEventTypeLeftMouseUp:
+    case NSEventTypeRightMouseDown:
+    case NSEventTypeRightMouseUp:
+    case NSEventTypeOtherMouseDown:
+    case NSEventTypeOtherMouseUp:
+    case NSEventTypeMouseMoved:
+    case NSEventTypeLeftMouseDragged:
+    case NSEventTypeRightMouseDragged:
+    case NSEventTypeOtherMouseDragged: {
+      // Drop all mouse events if a modal window has appeared above us.
+      // This helps make us behave as if the OS were running a "real" modal
+      // event loop.
+      id delegate = [self delegate];
+      if (delegate && [delegate isKindOfClass:[WindowDelegate class]]) {
+        nsCocoaWindow* widget = [(WindowDelegate*)delegate geckoWidget];
+        if (widget) {
+          if (gGeckoAppModalWindowList && (widget != gGeckoAppModalWindowList->window)) return;
+          if (widget->HasModalDescendents()) return;
+        }
+      }
+      break;
+    }
+    default:
+      break;
+  }
+
+  [super sendEvent:anEvent];
+}
+
+@end
+
+@implementation PopupWindow
+
+- (id)initWithContentRect:(NSRect)contentRect
+                styleMask:(NSUInteger)styleMask
+                  backing:(NSBackingStoreType)bufferingType
+                    defer:(BOOL)deferCreation {
+  NS_OBJC_BEGIN_TRY_BLOCK_RETURN;
+
+  mIsContextMenu = false;
+  return [super initWithContentRect:contentRect
+                          styleMask:styleMask
+                            backing:bufferingType
+                              defer:deferCreation];
+
+  NS_OBJC_END_TRY_BLOCK_RETURN(nil);
+}
+
+// Override the private API _backdropBleedAmount. This determines how much the
+// desktop wallpaper contributes to the vibrancy backdrop.
+// Return 0 in order to match what the system does for sheet windows and
+// _NSPopoverWindows.
+- (CGFloat)_backdropBleedAmount {
+  return 0.0;
+}
+
+// Override the private API shadowOptions.
+// The constants below were found in AppKit's implementations of the
+// shadowOptions method on the various window types.
+static const NSUInteger kWindowShadowOptionsNoShadow = 0;
+static const NSUInteger kWindowShadowOptionsMenu = 2;
+static const NSUInteger kWindowShadowOptionsTooltipMojaveOrLater = 4;
+- (NSUInteger)shadowOptions {
+  if (!self.hasShadow) {
+    return kWindowShadowOptionsNoShadow;
+  }
+
+  switch (self.shadowStyle) {
+    case StyleWindowShadow::None:
+      return kWindowShadowOptionsNoShadow;
+
+    case StyleWindowShadow::Default:  // we treat "default" as "default panel"
+    case StyleWindowShadow::Menu:
+      return kWindowShadowOptionsMenu;
+
+    case StyleWindowShadow::Tooltip:
+      if (nsCocoaFeatures::OnMojaveOrLater()) {
+        return kWindowShadowOptionsTooltipMojaveOrLater;
+      }
+      return kWindowShadowOptionsMenu;
+  }
+}
+
+- (BOOL)isContextMenu {
+  return mIsContextMenu;
+}
+
+- (void)setIsContextMenu:(BOOL)flag {
+  mIsContextMenu = flag;
+}
+
+- (BOOL)canBecomeMainWindow {
+  // This is overriden because the default is 'yes' when a titlebar is present.
+  return NO;
+}
+
+@end
+
+// According to Apple's docs on [NSWindow canBecomeKeyWindow] and [NSWindow
+// canBecomeMainWindow], windows without a title bar or resize bar can't (by
+// default) become key or main.  But if a window can't become key, it can't
+// accept keyboard input (bmo bug 393250).  And it should also be possible for
+// an otherwise "ordinary" window to become main.  We need to override these
+// two methods to make this happen.
+@implementation BorderlessWindow
+
+- (BOOL)canBecomeKeyWindow {
+  return YES;
+}
+
+- (void)sendEvent:(NSEvent*)anEvent {
+  NSEventType type = [anEvent type];
+
+  switch (type) {
+    case NSEventTypeScrollWheel:
+    case NSEventTypeLeftMouseDown:
+    case NSEventTypeLeftMouseUp:
+    case NSEventTypeRightMouseDown:
+    case NSEventTypeRightMouseUp:
+    case NSEventTypeOtherMouseDown:
+    case NSEventTypeOtherMouseUp:
+    case NSEventTypeMouseMoved:
+    case NSEventTypeLeftMouseDragged:
+    case NSEventTypeRightMouseDragged:
+    case NSEventTypeOtherMouseDragged: {
+      // Drop all mouse events if a modal window has appeared above us.
+      // This helps make us behave as if the OS were running a "real" modal
+      // event loop.
+      id delegate = [self delegate];
+      if (delegate && [delegate isKindOfClass:[WindowDelegate class]]) {
+        nsCocoaWindow* widget = [(WindowDelegate*)delegate geckoWidget];
+        if (widget) {
+          if (gGeckoAppModalWindowList && (widget != gGeckoAppModalWindowList->window)) return;
+          if (widget->HasModalDescendents()) return;
+        }
+      }
+      break;
+    }
+    default:
+      break;
+  }
+
+  [super sendEvent:anEvent];
+}
+
+// Apple's doc on this method says that the NSWindow class's default is not to
+// become main if the window isn't "visible" -- so we should replicate that
+// behavior here.  As best I can tell, the [NSWindow isVisible] method is an
+// accurate test of what Apple means by "visibility".
+- (BOOL)canBecomeMainWindow {
+  NS_OBJC_BEGIN_TRY_BLOCK_RETURN;
+
+  if (![self isVisible]) return NO;
+  return YES;
+
+  NS_OBJC_END_TRY_BLOCK_RETURN(NO);
+}
+
+// Retain and release "self" to avoid crashes when our widget (and its native
+// window) is closed as a result of processing a key equivalent (e.g.
+// Command+w or Command+q).  This workaround is only needed for a window
+// that can become key.
+- (BOOL)performKeyEquivalent:(NSEvent*)theEvent {
+  NS_OBJC_BEGIN_TRY_BLOCK_RETURN;
+
+  NSWindow* nativeWindow = [self retain];
+  BOOL retval = [super performKeyEquivalent:theEvent];
+  [nativeWindow release];
+  return retval;
+
+  NS_OBJC_END_TRY_BLOCK_RETURN(NO);
+}
+
+@end