Adding upstream version 115.8.0esr.upstream/115.8.0esr

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

1 files changed, 1463 insertions, 0 deletions

diff --git a/widget/gtk/WidgetStyleCache.cpp b/widget/gtk/WidgetStyleCache.cpp
new file mode 100644
index 0000000000..05bfd30142
--- /dev/null
+++ b/widget/gtk/WidgetStyleCache.cpp
@@ -0,0 +1,1463 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=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 <dlfcn.h>
+#include <gtk/gtk.h>
+#include "WidgetStyleCache.h"
+#include "gtkdrawing.h"
+#include "mozilla/Assertions.h"
+#include "mozilla/PodOperations.h"
+#include "mozilla/ScopeExit.h"
+#include "nsDebug.h"
+#include "nsPrintfCString.h"
+#include "nsString.h"
+
+#define STATE_FLAG_DIR_LTR (1U << 7)
+#define STATE_FLAG_DIR_RTL (1U << 8)
+static_assert(GTK_STATE_FLAG_DIR_LTR == STATE_FLAG_DIR_LTR &&
+                  GTK_STATE_FLAG_DIR_RTL == STATE_FLAG_DIR_RTL,
+              "incorrect direction state flags");
+
+enum class CSDStyle {
+  Unknown,
+  Solid,
+  Normal,
+};
+
+static bool gHeaderBarShouldDrawContainer = false;
+static bool gMaximizedHeaderBarShouldDrawContainer = false;
+static CSDStyle gCSDStyle = CSDStyle::Unknown;
+static GtkWidget* sWidgetStorage[MOZ_GTK_WIDGET_NODE_COUNT];
+static GtkStyleContext* sStyleStorage[MOZ_GTK_WIDGET_NODE_COUNT];
+
+static GtkStyleContext* GetWidgetRootStyle(WidgetNodeType aNodeType);
+static GtkStyleContext* GetCssNodeStyleInternal(WidgetNodeType aNodeType);
+
+static GtkWidget* CreateWindowWidget() {
+  GtkWidget* widget = gtk_window_new(GTK_WINDOW_POPUP);
+  MOZ_RELEASE_ASSERT(widget, "We're missing GtkWindow widget!");
+  gtk_widget_set_name(widget, "MozillaGtkWidget");
+  return widget;
+}
+
+static GtkWidget* CreateWindowContainerWidget() {
+  GtkWidget* widget = gtk_fixed_new();
+  gtk_container_add(GTK_CONTAINER(GetWidget(MOZ_GTK_WINDOW)), widget);
+  return widget;
+}
+
+static void AddToWindowContainer(GtkWidget* widget) {
+  gtk_container_add(GTK_CONTAINER(GetWidget(MOZ_GTK_WINDOW_CONTAINER)), widget);
+}
+
+static GtkWidget* CreateScrollbarWidget(WidgetNodeType aAppearance,
+                                        GtkOrientation aOrientation) {
+  GtkWidget* widget = gtk_scrollbar_new(aOrientation, nullptr);
+  AddToWindowContainer(widget);
+  return widget;
+}
+
+static GtkWidget* CreateCheckboxWidget() {
+  GtkWidget* widget = gtk_check_button_new_with_label("M");
+  AddToWindowContainer(widget);
+  return widget;
+}
+
+static GtkWidget* CreateRadiobuttonWidget() {
+  GtkWidget* widget = gtk_radio_button_new_with_label(nullptr, "M");
+  AddToWindowContainer(widget);
+  return widget;
+}
+
+static GtkWidget* CreateMenuPopupWidget() {
+  GtkWidget* widget = gtk_menu_new();
+  GtkStyleContext* style = gtk_widget_get_style_context(widget);
+  gtk_style_context_add_class(style, GTK_STYLE_CLASS_POPUP);
+  gtk_menu_attach_to_widget(GTK_MENU(widget), GetWidget(MOZ_GTK_WINDOW),
+                            nullptr);
+  return widget;
+}
+
+static GtkWidget* CreateProgressWidget() {
+  GtkWidget* widget = gtk_progress_bar_new();
+  AddToWindowContainer(widget);
+  return widget;
+}
+
+static GtkWidget* CreateTooltipWidget() {
+  MOZ_ASSERT(gtk_check_version(3, 20, 0) != nullptr,
+             "CreateTooltipWidget should be used for Gtk < 3.20 only.");
+  GtkWidget* widget = CreateWindowWidget();
+  GtkStyleContext* style = gtk_widget_get_style_context(widget);
+  gtk_style_context_add_class(style, GTK_STYLE_CLASS_TOOLTIP);
+  return widget;
+}
+
+static GtkWidget* CreateExpanderWidget() {
+  GtkWidget* widget = gtk_expander_new("M");
+  AddToWindowContainer(widget);
+  return widget;
+}
+
+static GtkWidget* CreateFrameWidget() {
+  GtkWidget* widget = gtk_frame_new(nullptr);
+  AddToWindowContainer(widget);
+  return widget;
+}
+
+static GtkWidget* CreateGripperWidget() {
+  GtkWidget* widget = gtk_handle_box_new();
+  AddToWindowContainer(widget);
+  return widget;
+}
+
+static GtkWidget* CreateToolbarWidget() {
+  GtkWidget* widget = gtk_toolbar_new();
+  gtk_container_add(GTK_CONTAINER(GetWidget(MOZ_GTK_GRIPPER)), widget);
+  return widget;
+}
+
+static GtkWidget* CreateToolbarSeparatorWidget() {
+  GtkWidget* widget = GTK_WIDGET(gtk_separator_tool_item_new());
+  AddToWindowContainer(widget);
+  return widget;
+}
+
+static GtkWidget* CreateButtonWidget() {
+  GtkWidget* widget = gtk_button_new_with_label("M");
+  AddToWindowContainer(widget);
+  return widget;
+}
+
+static GtkWidget* CreateToggleButtonWidget() {
+  GtkWidget* widget = gtk_toggle_button_new();
+  AddToWindowContainer(widget);
+  return widget;
+}
+
+static GtkWidget* CreateButtonArrowWidget() {
+  GtkWidget* widget = gtk_arrow_new(GTK_ARROW_DOWN, GTK_SHADOW_OUT);
+  gtk_container_add(GTK_CONTAINER(GetWidget(MOZ_GTK_TOGGLE_BUTTON)), widget);
+  gtk_widget_show(widget);
+  return widget;
+}
+
+static GtkWidget* CreateSpinWidget() {
+  GtkWidget* widget = gtk_spin_button_new(nullptr, 1, 0);
+  AddToWindowContainer(widget);
+  return widget;
+}
+
+static GtkWidget* CreateEntryWidget() {
+  GtkWidget* widget = gtk_entry_new();
+  AddToWindowContainer(widget);
+  return widget;
+}
+
+static GtkWidget* CreateComboBoxWidget() {
+  GtkWidget* widget = gtk_combo_box_new();
+  AddToWindowContainer(widget);
+  return widget;
+}
+
+typedef struct {
+  GType type;
+  GtkWidget** widget;
+} GtkInnerWidgetInfo;
+
+static void GetInnerWidget(GtkWidget* widget, gpointer client_data) {
+  auto info = static_cast<GtkInnerWidgetInfo*>(client_data);
+
+  if (G_TYPE_CHECK_INSTANCE_TYPE(widget, info->type)) {
+    *info->widget = widget;
+  }
+}
+
+static GtkWidget* CreateComboBoxButtonWidget() {
+  GtkWidget* comboBox = GetWidget(MOZ_GTK_COMBOBOX);
+  GtkWidget* comboBoxButton = nullptr;
+
+  /* Get its inner Button */
+  GtkInnerWidgetInfo info = {GTK_TYPE_TOGGLE_BUTTON, &comboBoxButton};
+  gtk_container_forall(GTK_CONTAINER(comboBox), GetInnerWidget, &info);
+
+  if (!comboBoxButton) {
+    /* Shouldn't be reached with current internal gtk implementation; we
+     * use a generic toggle button as last resort fallback to avoid
+     * crashing. */
+    comboBoxButton = GetWidget(MOZ_GTK_TOGGLE_BUTTON);
+  } else {
+    /* We need to have pointers to the inner widgets (button, separator, arrow)
+     * of the ComboBox to get the correct rendering from theme engines which
+     * special cases their look. Since the inner layout can change, we ask GTK
+     * to NULL our pointers when they are about to become invalid because the
+     * corresponding widgets don't exist anymore. It's the role of
+     * g_object_add_weak_pointer().
+     * Note that if we don't find the inner widgets (which shouldn't happen), we
+     * fallback to use generic "non-inner" widgets, and they don't need that
+     * kind of weak pointer since they are explicit children of gProtoLayout and
+     * as such GTK holds a strong reference to them. */
+    g_object_add_weak_pointer(
+        G_OBJECT(comboBoxButton),
+        reinterpret_cast<gpointer*>(sWidgetStorage) + MOZ_GTK_COMBOBOX_BUTTON);
+  }
+
+  return comboBoxButton;
+}
+
+static GtkWidget* CreateComboBoxArrowWidget() {
+  GtkWidget* comboBoxButton = GetWidget(MOZ_GTK_COMBOBOX_BUTTON);
+  GtkWidget* comboBoxArrow = nullptr;
+
+  /* Get the widgets inside the Button */
+  GtkWidget* buttonChild = gtk_bin_get_child(GTK_BIN(comboBoxButton));
+  if (GTK_IS_BOX(buttonChild)) {
+    /* appears-as-list = FALSE, cell-view = TRUE; the button
+     * contains an hbox. This hbox is there because the ComboBox
+     * needs to place a cell renderer, a separator, and an arrow in
+     * the button when appears-as-list is FALSE. */
+    GtkInnerWidgetInfo info = {GTK_TYPE_ARROW, &comboBoxArrow};
+    gtk_container_forall(GTK_CONTAINER(buttonChild), GetInnerWidget, &info);
+  } else if (GTK_IS_ARROW(buttonChild)) {
+    /* appears-as-list = TRUE, or cell-view = FALSE;
+     * the button only contains an arrow */
+    comboBoxArrow = buttonChild;
+  }
+
+  if (!comboBoxArrow) {
+    /* Shouldn't be reached with current internal gtk implementation;
+     * we gButtonArrowWidget as last resort fallback to avoid
+     * crashing. */
+    comboBoxArrow = GetWidget(MOZ_GTK_BUTTON_ARROW);
+  } else {
+    g_object_add_weak_pointer(
+        G_OBJECT(comboBoxArrow),
+        reinterpret_cast<gpointer*>(sWidgetStorage) + MOZ_GTK_COMBOBOX_ARROW);
+  }
+
+  return comboBoxArrow;
+}
+
+static GtkWidget* CreateComboBoxSeparatorWidget() {
+  // Ensure to search for separator only once as it can fail
+  // TODO - it won't initialize after ResetWidgetCache() call
+  static bool isMissingSeparator = false;
+  if (isMissingSeparator) return nullptr;
+
+  /* Get the widgets inside the Button */
+  GtkWidget* comboBoxSeparator = nullptr;
+  GtkWidget* buttonChild =
+      gtk_bin_get_child(GTK_BIN(GetWidget(MOZ_GTK_COMBOBOX_BUTTON)));
+  if (GTK_IS_BOX(buttonChild)) {
+    /* appears-as-list = FALSE, cell-view = TRUE; the button
+     * contains an hbox. This hbox is there because the ComboBox
+     * needs to place a cell renderer, a separator, and an arrow in
+     * the button when appears-as-list is FALSE. */
+    GtkInnerWidgetInfo info = {GTK_TYPE_SEPARATOR, &comboBoxSeparator};
+    gtk_container_forall(GTK_CONTAINER(buttonChild), GetInnerWidget, &info);
+  }
+
+  if (comboBoxSeparator) {
+    g_object_add_weak_pointer(G_OBJECT(comboBoxSeparator),
+                              reinterpret_cast<gpointer*>(sWidgetStorage) +
+                                  MOZ_GTK_COMBOBOX_SEPARATOR);
+  } else {
+    /* comboBoxSeparator may be NULL
+     * when "appears-as-list" = TRUE or "cell-view" = FALSE;
+     * if there is no separator, then we just won't paint it. */
+    isMissingSeparator = true;
+  }
+
+  return comboBoxSeparator;
+}
+
+static GtkWidget* CreateComboBoxEntryWidget() {
+  GtkWidget* widget = gtk_combo_box_new_with_entry();
+  AddToWindowContainer(widget);
+  return widget;
+}
+
+static GtkWidget* CreateComboBoxEntryTextareaWidget() {
+  GtkWidget* comboBoxTextarea = nullptr;
+
+  /* Get its inner Entry and Button */
+  GtkInnerWidgetInfo info = {GTK_TYPE_ENTRY, &comboBoxTextarea};
+  gtk_container_forall(GTK_CONTAINER(GetWidget(MOZ_GTK_COMBOBOX_ENTRY)),
+                       GetInnerWidget, &info);
+
+  if (!comboBoxTextarea) {
+    comboBoxTextarea = GetWidget(MOZ_GTK_ENTRY);
+  } else {
+    g_object_add_weak_pointer(
+        G_OBJECT(comboBoxTextarea),
+        reinterpret_cast<gpointer*>(sWidgetStorage) + MOZ_GTK_COMBOBOX_ENTRY);
+  }
+
+  return comboBoxTextarea;
+}
+
+static GtkWidget* CreateComboBoxEntryButtonWidget() {
+  GtkWidget* comboBoxButton = nullptr;
+
+  /* Get its inner Entry and Button */
+  GtkInnerWidgetInfo info = {GTK_TYPE_TOGGLE_BUTTON, &comboBoxButton};
+  gtk_container_forall(GTK_CONTAINER(GetWidget(MOZ_GTK_COMBOBOX_ENTRY)),
+                       GetInnerWidget, &info);
+
+  if (!comboBoxButton) {
+    comboBoxButton = GetWidget(MOZ_GTK_TOGGLE_BUTTON);
+  } else {
+    g_object_add_weak_pointer(G_OBJECT(comboBoxButton),
+                              reinterpret_cast<gpointer*>(sWidgetStorage) +
+                                  MOZ_GTK_COMBOBOX_ENTRY_BUTTON);
+  }
+
+  return comboBoxButton;
+}
+
+static GtkWidget* CreateComboBoxEntryArrowWidget() {
+  GtkWidget* comboBoxArrow = nullptr;
+
+  /* Get the Arrow inside the Button */
+  GtkWidget* buttonChild =
+      gtk_bin_get_child(GTK_BIN(GetWidget(MOZ_GTK_COMBOBOX_ENTRY_BUTTON)));
+
+  if (GTK_IS_BOX(buttonChild)) {
+    /* appears-as-list = FALSE, cell-view = TRUE; the button
+     * contains an hbox. This hbox is there because the ComboBox
+     * needs to place a cell renderer, a separator, and an arrow in
+     * the button when appears-as-list is FALSE. */
+    GtkInnerWidgetInfo info = {GTK_TYPE_ARROW, &comboBoxArrow};
+    gtk_container_forall(GTK_CONTAINER(buttonChild), GetInnerWidget, &info);
+  } else if (GTK_IS_ARROW(buttonChild)) {
+    /* appears-as-list = TRUE, or cell-view = FALSE;
+     * the button only contains an arrow */
+    comboBoxArrow = buttonChild;
+  }
+
+  if (!comboBoxArrow) {
+    /* Shouldn't be reached with current internal gtk implementation;
+     * we gButtonArrowWidget as last resort fallback to avoid
+     * crashing. */
+    comboBoxArrow = GetWidget(MOZ_GTK_BUTTON_ARROW);
+  } else {
+    g_object_add_weak_pointer(G_OBJECT(comboBoxArrow),
+                              reinterpret_cast<gpointer*>(sWidgetStorage) +
+                                  MOZ_GTK_COMBOBOX_ENTRY_ARROW);
+  }
+
+  return comboBoxArrow;
+}
+
+static GtkWidget* CreateScrolledWindowWidget() {
+  GtkWidget* widget = gtk_scrolled_window_new(nullptr, nullptr);
+  AddToWindowContainer(widget);
+  return widget;
+}
+
+static GtkWidget* CreateTreeViewWidget() {
+  GtkWidget* widget = gtk_tree_view_new();
+  AddToWindowContainer(widget);
+  return widget;
+}
+
+static GtkWidget* CreateTreeHeaderCellWidget() {
+  /*
+   * Some GTK engines paint the first and last cell
+   * of a TreeView header with a highlight.
+   * Since we do not know where our widget will be relative
+   * to the other buttons in the TreeView header, we must
+   * paint it as a button that is between two others,
+   * thus ensuring it is neither the first or last button
+   * in the header.
+   * GTK doesn't give us a way to do this explicitly,
+   * so we must paint with a button that is between two
+   * others.
+   */
+  GtkTreeViewColumn* firstTreeViewColumn;
+  GtkTreeViewColumn* middleTreeViewColumn;
+  GtkTreeViewColumn* lastTreeViewColumn;
+
+  GtkWidget* treeView = GetWidget(MOZ_GTK_TREEVIEW);
+
+  /* Create and append our three columns */
+  firstTreeViewColumn = gtk_tree_view_column_new();
+  gtk_tree_view_column_set_title(firstTreeViewColumn, "M");
+  gtk_tree_view_append_column(GTK_TREE_VIEW(treeView), firstTreeViewColumn);
+
+  middleTreeViewColumn = gtk_tree_view_column_new();
+  gtk_tree_view_column_set_title(middleTreeViewColumn, "M");
+  gtk_tree_view_append_column(GTK_TREE_VIEW(treeView), middleTreeViewColumn);
+
+  lastTreeViewColumn = gtk_tree_view_column_new();
+  gtk_tree_view_column_set_title(lastTreeViewColumn, "M");
+  gtk_tree_view_append_column(GTK_TREE_VIEW(treeView), lastTreeViewColumn);
+
+  /* Use the middle column's header for our button */
+  return gtk_tree_view_column_get_button(middleTreeViewColumn);
+}
+
+static GtkWidget* CreateTreeHeaderSortArrowWidget() {
+  /* TODO, but it can't be NULL */
+  GtkWidget* widget = gtk_button_new();
+  AddToWindowContainer(widget);
+  return widget;
+}
+
+static GtkWidget* CreateHPanedWidget() {
+  GtkWidget* widget = gtk_paned_new(GTK_ORIENTATION_HORIZONTAL);
+  AddToWindowContainer(widget);
+  return widget;
+}
+
+static GtkWidget* CreateVPanedWidget() {
+  GtkWidget* widget = gtk_paned_new(GTK_ORIENTATION_VERTICAL);
+  AddToWindowContainer(widget);
+  return widget;
+}
+
+static GtkWidget* CreateScaleWidget(GtkOrientation aOrientation) {
+  GtkWidget* widget = gtk_scale_new(aOrientation, nullptr);
+  AddToWindowContainer(widget);
+  return widget;
+}
+
+static GtkWidget* CreateNotebookWidget() {
+  GtkWidget* widget = gtk_notebook_new();
+  AddToWindowContainer(widget);
+  return widget;
+}
+
+static bool HasBackground(GtkStyleContext* aStyle) {
+  GdkRGBA gdkColor;
+  gtk_style_context_get_background_color(aStyle, GTK_STATE_FLAG_NORMAL,
+                                         &gdkColor);
+  if (gdkColor.alpha != 0.0) {
+    return true;
+  }
+
+  GValue value = G_VALUE_INIT;
+  gtk_style_context_get_property(aStyle, "background-image",
+                                 GTK_STATE_FLAG_NORMAL, &value);
+  auto cleanup = mozilla::MakeScopeExit([&] { g_value_unset(&value); });
+  return g_value_get_boxed(&value);
+}
+
+static void CreateHeaderBarWidget(WidgetNodeType aAppearance) {
+  GtkWidget* window = gtk_window_new(GTK_WINDOW_TOPLEVEL);
+  GtkStyleContext* windowStyle = gtk_widget_get_style_context(window);
+
+  // Headerbar has to be placed to window with csd or solid-csd style
+  // to properly draw the decorated.
+  gtk_style_context_add_class(windowStyle,
+                              IsSolidCSDStyleUsed() ? "solid-csd" : "csd");
+
+  GtkWidget* fixed = gtk_fixed_new();
+  GtkStyleContext* fixedStyle = gtk_widget_get_style_context(fixed);
+  gtk_style_context_add_class(fixedStyle, "titlebar");
+
+  GtkWidget* headerBar = gtk_header_bar_new();
+
+  // Emulate what create_titlebar() at gtkwindow.c does.
+  GtkStyleContext* headerBarStyle = gtk_widget_get_style_context(headerBar);
+  gtk_style_context_add_class(headerBarStyle, "titlebar");
+
+  // TODO: Define default-decoration titlebar style as workaround
+  // to ensure the titlebar buttons does not overflow outside.
+  // Recently the titlebar size is calculated as
+  // tab size + titlebar border/padding (default-decoration has 6px padding
+  // at default Adwaita theme).
+  // We need to fix titlebar size calculation to also include
+  // titlebar button sizes. (Bug 1419442)
+  gtk_style_context_add_class(headerBarStyle, "default-decoration");
+
+  sWidgetStorage[aAppearance] = headerBar;
+  if (aAppearance == MOZ_GTK_HEADER_BAR_MAXIMIZED) {
+    MOZ_ASSERT(!sWidgetStorage[MOZ_GTK_HEADERBAR_WINDOW_MAXIMIZED],
+               "Window widget is already created!");
+    MOZ_ASSERT(!sWidgetStorage[MOZ_GTK_HEADERBAR_FIXED_MAXIMIZED],
+               "Fixed widget is already created!");
+
+    gtk_style_context_add_class(windowStyle, "maximized");
+
+    sWidgetStorage[MOZ_GTK_HEADERBAR_WINDOW_MAXIMIZED] = window;
+    sWidgetStorage[MOZ_GTK_HEADERBAR_FIXED_MAXIMIZED] = fixed;
+  } else {
+    MOZ_ASSERT(!sWidgetStorage[MOZ_GTK_HEADERBAR_WINDOW],
+               "Window widget is already created!");
+    MOZ_ASSERT(!sWidgetStorage[MOZ_GTK_HEADERBAR_FIXED],
+               "Fixed widget is already created!");
+    sWidgetStorage[MOZ_GTK_HEADERBAR_WINDOW] = window;
+    sWidgetStorage[MOZ_GTK_HEADERBAR_FIXED] = fixed;
+  }
+
+  gtk_container_add(GTK_CONTAINER(window), fixed);
+  gtk_container_add(GTK_CONTAINER(fixed), headerBar);
+
+  gtk_style_context_invalidate(headerBarStyle);
+  gtk_style_context_invalidate(fixedStyle);
+
+  // Some themes like Elementary's style the container of the headerbar rather
+  // than the header bar itself.
+  bool& shouldDrawContainer = aAppearance == MOZ_GTK_HEADER_BAR
+                                  ? gHeaderBarShouldDrawContainer
+                                  : gMaximizedHeaderBarShouldDrawContainer;
+  shouldDrawContainer = [&] {
+    const bool headerBarHasBackground = HasBackground(headerBarStyle);
+    if (headerBarHasBackground && GetBorderRadius(headerBarStyle)) {
+      return false;
+    }
+    if (HasBackground(fixedStyle) &&
+        (GetBorderRadius(fixedStyle) || !headerBarHasBackground)) {
+      return true;
+    }
+    return false;
+  }();
+}
+
+#define ICON_SCALE_VARIANTS 2
+
+static void LoadWidgetIconPixbuf(GtkWidget* aWidgetIcon) {
+  GtkStyleContext* style = gtk_widget_get_style_context(aWidgetIcon);
+
+  const gchar* iconName;
+  GtkIconSize gtkIconSize;
+  gtk_image_get_icon_name(GTK_IMAGE(aWidgetIcon), &iconName, &gtkIconSize);
+
+  gint iconWidth, iconHeight;
+  gtk_icon_size_lookup(gtkIconSize, &iconWidth, &iconHeight);
+
+  /* Those are available since Gtk+ 3.10 as well as GtkHeaderBar */
+  for (int scale = 1; scale < ICON_SCALE_VARIANTS + 1; scale++) {
+    GtkIconInfo* gtkIconInfo = gtk_icon_theme_lookup_icon_for_scale(
+        gtk_icon_theme_get_default(), iconName, iconWidth, scale,
+        (GtkIconLookupFlags)0);
+
+    if (!gtkIconInfo) {
+      // We miss the icon, nothing to do here.
+      return;
+    }
+
+    gboolean unused;
+    GdkPixbuf* iconPixbuf = gtk_icon_info_load_symbolic_for_context(
+        gtkIconInfo, style, &unused, nullptr);
+    g_object_unref(G_OBJECT(gtkIconInfo));
+
+    cairo_surface_t* iconSurface =
+        gdk_cairo_surface_create_from_pixbuf(iconPixbuf, scale, nullptr);
+    g_object_unref(iconPixbuf);
+
+    nsPrintfCString surfaceName("MozillaIconSurface%d", scale);
+    g_object_set_data_full(G_OBJECT(aWidgetIcon), surfaceName.get(),
+                           iconSurface, (GDestroyNotify)cairo_surface_destroy);
+  }
+}
+
+cairo_surface_t* GetWidgetIconSurface(GtkWidget* aWidgetIcon, int aScale) {
+  if (aScale > ICON_SCALE_VARIANTS) {
+    aScale = ICON_SCALE_VARIANTS;
+  }
+
+  nsPrintfCString surfaceName("MozillaIconSurface%d", aScale);
+  return (cairo_surface_t*)g_object_get_data(G_OBJECT(aWidgetIcon),
+                                             surfaceName.get());
+}
+
+static void CreateHeaderBarButton(GtkWidget* aParentWidget,
+                                  WidgetNodeType aAppearance) {
+  GtkWidget* widget = gtk_button_new();
+
+  // We have to add button to widget hierarchy now to pick
+  // right icon style at LoadWidgetIconPixbuf().
+  if (GTK_IS_BOX(aParentWidget)) {
+    gtk_box_pack_start(GTK_BOX(aParentWidget), widget, FALSE, FALSE, 0);
+  } else {
+    gtk_container_add(GTK_CONTAINER(aParentWidget), widget);
+  }
+
+  // We bypass GetWidget() here because we create all titlebar
+  // buttons at once when a first one is requested.
+  NS_ASSERTION(!sWidgetStorage[aAppearance],
+               "Titlebar button is already created!");
+  sWidgetStorage[aAppearance] = widget;
+
+  // We need to show the button widget now as GtkBox does not
+  // place invisible widgets and we'll miss first-child/last-child
+  // css selectors at the buttons otherwise.
+  gtk_widget_show(widget);
+
+  GtkStyleContext* style = gtk_widget_get_style_context(widget);
+  gtk_style_context_add_class(style, "titlebutton");
+
+  GtkWidget* image = nullptr;
+  switch (aAppearance) {
+    case MOZ_GTK_HEADER_BAR_BUTTON_CLOSE:
+      gtk_style_context_add_class(style, "close");
+      image = gtk_image_new_from_icon_name("window-close-symbolic",
+                                           GTK_ICON_SIZE_MENU);
+      break;
+    case MOZ_GTK_HEADER_BAR_BUTTON_MINIMIZE:
+      gtk_style_context_add_class(style, "minimize");
+      image = gtk_image_new_from_icon_name("window-minimize-symbolic",
+                                           GTK_ICON_SIZE_MENU);
+      break;
+
+    case MOZ_GTK_HEADER_BAR_BUTTON_MAXIMIZE:
+      gtk_style_context_add_class(style, "maximize");
+      image = gtk_image_new_from_icon_name("window-maximize-symbolic",
+                                           GTK_ICON_SIZE_MENU);
+      break;
+
+    case MOZ_GTK_HEADER_BAR_BUTTON_MAXIMIZE_RESTORE:
+      gtk_style_context_add_class(style, "maximize");
+      image = gtk_image_new_from_icon_name("window-restore-symbolic",
+                                           GTK_ICON_SIZE_MENU);
+      break;
+    default:
+      break;
+  }
+
+  gtk_widget_set_valign(widget, GTK_ALIGN_CENTER);
+  g_object_set(image, "use-fallback", TRUE, NULL);
+  gtk_container_add(GTK_CONTAINER(widget), image);
+
+  // We bypass GetWidget() here by explicit sWidgetStorage[] update so
+  // invalidate the style as well as GetWidget() does.
+  style = gtk_widget_get_style_context(image);
+  gtk_style_context_invalidate(style);
+
+  LoadWidgetIconPixbuf(image);
+}
+
+static bool IsToolbarButtonEnabled(ButtonLayout* aButtonLayout,
+                                   size_t aButtonNums,
+                                   WidgetNodeType aAppearance) {
+  for (size_t i = 0; i < aButtonNums; i++) {
+    if (aButtonLayout[i].mType == aAppearance) {
+      return true;
+    }
+  }
+  return false;
+}
+
+bool IsSolidCSDStyleUsed() {
+  if (gCSDStyle == CSDStyle::Unknown) {
+    bool solid;
+    {
+      GtkWidget* window = gtk_window_new(GTK_WINDOW_TOPLEVEL);
+      gtk_window_set_titlebar(GTK_WINDOW(window), gtk_header_bar_new());
+      gtk_widget_realize(window);
+      GtkStyleContext* windowStyle = gtk_widget_get_style_context(window);
+      solid = gtk_style_context_has_class(windowStyle, "solid-csd");
+      gtk_widget_destroy(window);
+    }
+    gCSDStyle = solid ? CSDStyle::Solid : CSDStyle::Normal;
+  }
+  return gCSDStyle == CSDStyle::Solid;
+}
+
+static void CreateHeaderBarButtons() {
+  GtkWidget* headerBar = sWidgetStorage[MOZ_GTK_HEADER_BAR];
+  MOZ_ASSERT(headerBar, "We're missing header bar widget!");
+
+  gint buttonSpacing = 6;
+  g_object_get(headerBar, "spacing", &buttonSpacing, nullptr);
+
+  GtkWidget* buttonBox = gtk_box_new(GTK_ORIENTATION_HORIZONTAL, buttonSpacing);
+  gtk_container_add(GTK_CONTAINER(headerBar), buttonBox);
+  // We support only LTR headerbar layout for now.
+  gtk_style_context_add_class(gtk_widget_get_style_context(buttonBox),
+                              GTK_STYLE_CLASS_LEFT);
+
+  ButtonLayout buttonLayout[TOOLBAR_BUTTONS];
+
+  size_t activeButtons =
+      GetGtkHeaderBarButtonLayout(mozilla::Span(buttonLayout), nullptr);
+
+  if (IsToolbarButtonEnabled(buttonLayout, activeButtons,
+                             MOZ_GTK_HEADER_BAR_BUTTON_MINIMIZE)) {
+    CreateHeaderBarButton(buttonBox, MOZ_GTK_HEADER_BAR_BUTTON_MINIMIZE);
+  }
+  if (IsToolbarButtonEnabled(buttonLayout, activeButtons,
+                             MOZ_GTK_HEADER_BAR_BUTTON_MAXIMIZE)) {
+    CreateHeaderBarButton(buttonBox, MOZ_GTK_HEADER_BAR_BUTTON_MAXIMIZE);
+    // We don't pack "restore" headerbar button to box as it's an icon
+    // placeholder. Pack it only to header bar to get correct style.
+    CreateHeaderBarButton(GetWidget(MOZ_GTK_HEADER_BAR_MAXIMIZED),
+                          MOZ_GTK_HEADER_BAR_BUTTON_MAXIMIZE_RESTORE);
+  }
+  if (IsToolbarButtonEnabled(buttonLayout, activeButtons,
+                             MOZ_GTK_HEADER_BAR_BUTTON_CLOSE)) {
+    CreateHeaderBarButton(buttonBox, MOZ_GTK_HEADER_BAR_BUTTON_CLOSE);
+  }
+}
+
+static void CreateHeaderBar() {
+  CreateHeaderBarWidget(MOZ_GTK_HEADER_BAR);
+  CreateHeaderBarWidget(MOZ_GTK_HEADER_BAR_MAXIMIZED);
+  CreateHeaderBarButtons();
+}
+
+static GtkWidget* CreateWidget(WidgetNodeType aAppearance) {
+  switch (aAppearance) {
+    case MOZ_GTK_WINDOW:
+      return CreateWindowWidget();
+    case MOZ_GTK_WINDOW_CONTAINER:
+      return CreateWindowContainerWidget();
+    case MOZ_GTK_CHECKBUTTON_CONTAINER:
+      return CreateCheckboxWidget();
+    case MOZ_GTK_PROGRESSBAR:
+      return CreateProgressWidget();
+    case MOZ_GTK_RADIOBUTTON_CONTAINER:
+      return CreateRadiobuttonWidget();
+    case MOZ_GTK_SCROLLBAR_VERTICAL:
+      return CreateScrollbarWidget(aAppearance, GTK_ORIENTATION_VERTICAL);
+    case MOZ_GTK_MENUPOPUP:
+      return CreateMenuPopupWidget();
+    case MOZ_GTK_EXPANDER:
+      return CreateExpanderWidget();
+    case MOZ_GTK_FRAME:
+      return CreateFrameWidget();
+    case MOZ_GTK_GRIPPER:
+      return CreateGripperWidget();
+    case MOZ_GTK_TOOLBAR:
+      return CreateToolbarWidget();
+    case MOZ_GTK_TOOLBAR_SEPARATOR:
+      return CreateToolbarSeparatorWidget();
+    case MOZ_GTK_SPINBUTTON:
+      return CreateSpinWidget();
+    case MOZ_GTK_BUTTON:
+      return CreateButtonWidget();
+    case MOZ_GTK_TOGGLE_BUTTON:
+      return CreateToggleButtonWidget();
+    case MOZ_GTK_BUTTON_ARROW:
+      return CreateButtonArrowWidget();
+    case MOZ_GTK_ENTRY:
+    case MOZ_GTK_DROPDOWN_ENTRY:
+      return CreateEntryWidget();
+    case MOZ_GTK_SCROLLED_WINDOW:
+      return CreateScrolledWindowWidget();
+    case MOZ_GTK_TREEVIEW:
+      return CreateTreeViewWidget();
+    case MOZ_GTK_TREE_HEADER_CELL:
+      return CreateTreeHeaderCellWidget();
+    case MOZ_GTK_TREE_HEADER_SORTARROW:
+      return CreateTreeHeaderSortArrowWidget();
+    case MOZ_GTK_SPLITTER_HORIZONTAL:
+      return CreateHPanedWidget();
+    case MOZ_GTK_SPLITTER_VERTICAL:
+      return CreateVPanedWidget();
+    case MOZ_GTK_SCALE_HORIZONTAL:
+      return CreateScaleWidget(GTK_ORIENTATION_HORIZONTAL);
+    case MOZ_GTK_SCALE_VERTICAL:
+      return CreateScaleWidget(GTK_ORIENTATION_VERTICAL);
+    case MOZ_GTK_NOTEBOOK:
+      return CreateNotebookWidget();
+    case MOZ_GTK_COMBOBOX:
+      return CreateComboBoxWidget();
+    case MOZ_GTK_COMBOBOX_BUTTON:
+      return CreateComboBoxButtonWidget();
+    case MOZ_GTK_COMBOBOX_ARROW:
+      return CreateComboBoxArrowWidget();
+    case MOZ_GTK_COMBOBOX_SEPARATOR:
+      return CreateComboBoxSeparatorWidget();
+    case MOZ_GTK_COMBOBOX_ENTRY:
+      return CreateComboBoxEntryWidget();
+    case MOZ_GTK_COMBOBOX_ENTRY_TEXTAREA:
+      return CreateComboBoxEntryTextareaWidget();
+    case MOZ_GTK_COMBOBOX_ENTRY_BUTTON:
+      return CreateComboBoxEntryButtonWidget();
+    case MOZ_GTK_COMBOBOX_ENTRY_ARROW:
+      return CreateComboBoxEntryArrowWidget();
+    case MOZ_GTK_HEADERBAR_WINDOW:
+    case MOZ_GTK_HEADERBAR_WINDOW_MAXIMIZED:
+    case MOZ_GTK_HEADERBAR_FIXED:
+    case MOZ_GTK_HEADERBAR_FIXED_MAXIMIZED:
+    case MOZ_GTK_HEADER_BAR:
+    case MOZ_GTK_HEADER_BAR_MAXIMIZED:
+    case MOZ_GTK_HEADER_BAR_BUTTON_CLOSE:
+    case MOZ_GTK_HEADER_BAR_BUTTON_MINIMIZE:
+    case MOZ_GTK_HEADER_BAR_BUTTON_MAXIMIZE:
+    case MOZ_GTK_HEADER_BAR_BUTTON_MAXIMIZE_RESTORE:
+      /* Create header bar widgets once and fill with child elements as we need
+         the header bar fully configured to get a correct style */
+      CreateHeaderBar();
+      return sWidgetStorage[aAppearance];
+    default:
+      /* Not implemented */
+      return nullptr;
+  }
+}
+
+GtkWidget* GetWidget(WidgetNodeType aAppearance) {
+  GtkWidget* widget = sWidgetStorage[aAppearance];
+  if (!widget) {
+    widget = CreateWidget(aAppearance);
+    // Some widgets (MOZ_GTK_COMBOBOX_SEPARATOR for instance) may not be
+    // available or implemented.
+    if (!widget) {
+      return nullptr;
+    }
+    // In GTK versions prior to 3.18, automatic invalidation of style contexts
+    // for widgets was delayed until the next resize event.  Gecko however,
+    // typically uses the style context before the resize event runs and so an
+    // explicit invalidation may be required.  This is necessary if a style
+    // property was retrieved before all changes were made to the style
+    // context.  One such situation is where gtk_button_construct_child()
+    // retrieves the style property "image-spacing" during construction of the
+    // GtkButton, before its parent is set to provide inheritance of ancestor
+    // properties.  More recent GTK versions do not need this, but do not
+    // re-resolve until required and so invalidation does not trigger
+    // unnecessary resolution in general.
+    GtkStyleContext* style = gtk_widget_get_style_context(widget);
+    gtk_style_context_invalidate(style);
+
+    sWidgetStorage[aAppearance] = widget;
+  }
+  return widget;
+}
+
+static void AddStyleClassesFromStyle(GtkStyleContext* aDest,
+                                     GtkStyleContext* aSrc) {
+  GList* classes = gtk_style_context_list_classes(aSrc);
+  for (GList* link = classes; link; link = link->next) {
+    gtk_style_context_add_class(aDest, static_cast<gchar*>(link->data));
+  }
+  g_list_free(classes);
+}
+
+GtkStyleContext* CreateStyleForWidget(GtkWidget* aWidget,
+                                      GtkStyleContext* aParentStyle) {
+  static auto sGtkWidgetClassGetCSSName =
+      reinterpret_cast<const char* (*)(GtkWidgetClass*)>(
+          dlsym(RTLD_DEFAULT, "gtk_widget_class_get_css_name"));
+
+  GtkWidgetClass* widgetClass = GTK_WIDGET_GET_CLASS(aWidget);
+  const gchar* name = sGtkWidgetClassGetCSSName
+                          ? sGtkWidgetClassGetCSSName(widgetClass)
+                          : nullptr;
+
+  GtkStyleContext* context =
+      CreateCSSNode(name, aParentStyle, G_TYPE_FROM_CLASS(widgetClass));
+
+  // Classes are stored on the style context instead of the path so that any
+  // future gtk_style_context_save() will inherit classes on the head CSS
+  // node, in the same way as happens when called on a style context owned by
+  // a widget.
+  //
+  // Classes can be stored on a GtkCssNodeDeclaration and/or the path.
+  // gtk_style_context_save() reuses the GtkCssNodeDeclaration, and appends a
+  // new object to the path, without copying the classes from the old path
+  // head.  The new head picks up classes from the GtkCssNodeDeclaration, but
+  // not the path.  GtkWidgets store their classes on the
+  // GtkCssNodeDeclaration, so make sure to add classes there.
+  //
+  // Picking up classes from the style context also means that
+  // https://bugzilla.gnome.org/show_bug.cgi?id=767312, which can stop
+  // gtk_widget_path_append_for_widget() from finding classes in GTK 3.20,
+  // is not a problem.
+  GtkStyleContext* widgetStyle = gtk_widget_get_style_context(aWidget);
+  AddStyleClassesFromStyle(context, widgetStyle);
+
+  // Release any floating reference on aWidget.
+  g_object_ref_sink(aWidget);
+  g_object_unref(aWidget);
+
+  return context;
+}
+
+static GtkStyleContext* CreateStyleForWidget(GtkWidget* aWidget,
+                                             WidgetNodeType aParentType) {
+  return CreateStyleForWidget(aWidget, GetWidgetRootStyle(aParentType));
+}
+
+GtkStyleContext* CreateCSSNode(const char* aName, GtkStyleContext* aParentStyle,
+                               GType aType) {
+  static auto sGtkWidgetPathIterSetObjectName =
+      reinterpret_cast<void (*)(GtkWidgetPath*, gint, const char*)>(
+          dlsym(RTLD_DEFAULT, "gtk_widget_path_iter_set_object_name"));
+
+  GtkWidgetPath* path;
+  if (aParentStyle) {
+    path = gtk_widget_path_copy(gtk_style_context_get_path(aParentStyle));
+    // Copy classes from the parent style context to its corresponding node in
+    // the path, because GTK will only match against ancestor classes if they
+    // are on the path.
+    GList* classes = gtk_style_context_list_classes(aParentStyle);
+    for (GList* link = classes; link; link = link->next) {
+      gtk_widget_path_iter_add_class(path, -1, static_cast<gchar*>(link->data));
+    }
+    g_list_free(classes);
+  } else {
+    path = gtk_widget_path_new();
+  }
+
+  gtk_widget_path_append_type(path, aType);
+
+  if (sGtkWidgetPathIterSetObjectName) {
+    (*sGtkWidgetPathIterSetObjectName)(path, -1, aName);
+  }
+
+  GtkStyleContext* context = gtk_style_context_new();
+  gtk_style_context_set_path(context, path);
+  gtk_style_context_set_parent(context, aParentStyle);
+  gtk_widget_path_unref(path);
+
+  // In GTK 3.4, gtk_render_* functions use |theming_engine| on the style
+  // context without ensuring any style resolution sets it appropriately
+  // in style_data_lookup(). e.g.
+  // https://git.gnome.org/browse/gtk+/tree/gtk/gtkstylecontext.c?h=3.4.4#n3847
+  //
+  // That can result in incorrect drawing on first draw.  To work around this,
+  // force a style look-up to set |theming_engine|.  It is sufficient to do
+  // this only on context creation, instead of after every modification to the
+  // context, because themes typically (Ambiance and oxygen-gtk, at least) set
+  // the "engine" property with the '*' selector.
+  if (GTK_MAJOR_VERSION == 3 && gtk_get_minor_version() < 6) {
+    GdkRGBA unused;
+    gtk_style_context_get_color(context, GTK_STATE_FLAG_NORMAL, &unused);
+  }
+
+  return context;
+}
+
+// Return a style context matching that of the root CSS node of a widget.
+// This is used by all GTK versions.
+static GtkStyleContext* GetWidgetRootStyle(WidgetNodeType aNodeType) {
+  GtkStyleContext* style = sStyleStorage[aNodeType];
+  if (style) return style;
+
+  switch (aNodeType) {
+    case MOZ_GTK_MENUITEM:
+      style = CreateStyleForWidget(gtk_menu_item_new(), MOZ_GTK_MENUPOPUP);
+      break;
+    case MOZ_GTK_TEXT_VIEW:
+      style =
+          CreateStyleForWidget(gtk_text_view_new(), MOZ_GTK_SCROLLED_WINDOW);
+      break;
+    case MOZ_GTK_TOOLTIP:
+      if (gtk_check_version(3, 20, 0) != nullptr) {
+        // The tooltip style class is added first in CreateTooltipWidget()
+        // and transfered to style in CreateStyleForWidget().
+        GtkWidget* tooltipWindow = CreateTooltipWidget();
+        style = CreateStyleForWidget(tooltipWindow, nullptr);
+        gtk_widget_destroy(tooltipWindow);  // Release GtkWindow self-reference.
+      } else {
+        // We create this from the path because GtkTooltipWindow is not public.
+        style = CreateCSSNode("tooltip", nullptr, GTK_TYPE_TOOLTIP);
+        gtk_style_context_add_class(style, GTK_STYLE_CLASS_BACKGROUND);
+      }
+      break;
+    case MOZ_GTK_TOOLTIP_BOX:
+      style = CreateStyleForWidget(gtk_box_new(GTK_ORIENTATION_HORIZONTAL, 0),
+                                   MOZ_GTK_TOOLTIP);
+      break;
+    case MOZ_GTK_TOOLTIP_BOX_LABEL:
+      style = CreateStyleForWidget(gtk_label_new(nullptr), MOZ_GTK_TOOLTIP_BOX);
+      break;
+    default:
+      GtkWidget* widget = GetWidget(aNodeType);
+      MOZ_ASSERT(widget);
+      return gtk_widget_get_style_context(widget);
+  }
+
+  MOZ_ASSERT(style);
+  sStyleStorage[aNodeType] = style;
+  return style;
+}
+
+static GtkStyleContext* CreateChildCSSNode(const char* aName,
+                                           WidgetNodeType aParentNodeType) {
+  return CreateCSSNode(aName, GetCssNodeStyleInternal(aParentNodeType));
+}
+
+// Create a style context equivalent to a saved root style context of
+// |aAppearance| with |aStyleClass| as an additional class.  This is used to
+// produce a context equivalent to what GTK versions < 3.20 use for many
+// internal parts of widgets.
+static GtkStyleContext* CreateSubStyleWithClass(WidgetNodeType aAppearance,
+                                                const gchar* aStyleClass) {
+  static auto sGtkWidgetPathIterGetObjectName =
+      reinterpret_cast<const char* (*)(const GtkWidgetPath*, gint)>(
+          dlsym(RTLD_DEFAULT, "gtk_widget_path_iter_get_object_name"));
+
+  GtkStyleContext* parentStyle = GetWidgetRootStyle(aAppearance);
+
+  // Create a new context that behaves like |parentStyle| would after
+  // gtk_style_context_save(parentStyle).
+  //
+  // Avoiding gtk_style_context_save() avoids the need to manage the
+  // restore, and a new context permits caching style resolution.
+  //
+  // gtk_style_context_save(context) changes the node hierarchy of |context|
+  // to add a new GtkCssNodeDeclaration that is a copy of its original node.
+  // The new node is a child of the original node, and so the new heirarchy is
+  // one level deeper.  The new node receives the same classes as the
+  // original, but any changes to the classes on |context| will change only
+  // the new node.  The new node inherits properties from the original node
+  // (which retains the original heirarchy and classes) and matches CSS rules
+  // with the new heirarchy and any changes to the classes.
+  //
+  // The change in hierarchy can produce some surprises in matching theme CSS
+  // rules (e.g. https://bugzilla.gnome.org/show_bug.cgi?id=761870#c2), but it
+  // is important here to produce the same behavior so that rules match the
+  // same widget parts in Gecko as they do in GTK.
+  //
+  // When using public GTK API to construct style contexts, a widget path is
+  // required.  CSS rules are not matched against the style context heirarchy
+  // but according to the heirarchy in the widget path.  The path that matches
+  // the same CSS rules as a saved context is like the path of |parentStyle|
+  // but with an extra copy of the head (last) object appended.  Setting
+  // |parentStyle| as the parent context provides the same inheritance of
+  // properties from the widget root node.
+  const GtkWidgetPath* parentPath = gtk_style_context_get_path(parentStyle);
+  const gchar* name = sGtkWidgetPathIterGetObjectName
+                          ? sGtkWidgetPathIterGetObjectName(parentPath, -1)
+                          : nullptr;
+  GType objectType = gtk_widget_path_get_object_type(parentPath);
+
+  GtkStyleContext* style = CreateCSSNode(name, parentStyle, objectType);
+
+  // Start with the same classes on the new node as were on |parentStyle|.
+  // GTK puts no regions or junction_sides on widget root nodes, and so there
+  // is no need to copy these.
+  AddStyleClassesFromStyle(style, parentStyle);
+
+  gtk_style_context_add_class(style, aStyleClass);
+  return style;
+}
+
+/* GetCssNodeStyleInternal is used by Gtk >= 3.20 */
+static GtkStyleContext* GetCssNodeStyleInternal(WidgetNodeType aNodeType) {
+  GtkStyleContext* style = sStyleStorage[aNodeType];
+  if (style) return style;
+
+  switch (aNodeType) {
+    case MOZ_GTK_SCROLLBAR_CONTENTS_VERTICAL:
+      style = CreateChildCSSNode("contents", MOZ_GTK_SCROLLBAR_VERTICAL);
+      break;
+    case MOZ_GTK_SCROLLBAR_TROUGH_VERTICAL:
+      style = CreateChildCSSNode(GTK_STYLE_CLASS_TROUGH,
+                                 MOZ_GTK_SCROLLBAR_CONTENTS_VERTICAL);
+      break;
+    case MOZ_GTK_SCROLLBAR_THUMB_VERTICAL:
+      style = CreateChildCSSNode(GTK_STYLE_CLASS_SLIDER,
+                                 MOZ_GTK_SCROLLBAR_TROUGH_VERTICAL);
+      break;
+    case MOZ_GTK_RADIOBUTTON:
+      style = CreateChildCSSNode(GTK_STYLE_CLASS_RADIO,
+                                 MOZ_GTK_RADIOBUTTON_CONTAINER);
+      break;
+    case MOZ_GTK_CHECKBUTTON:
+      style = CreateChildCSSNode(GTK_STYLE_CLASS_CHECK,
+                                 MOZ_GTK_CHECKBUTTON_CONTAINER);
+      break;
+    case MOZ_GTK_PROGRESS_TROUGH:
+      /* Progress bar background (trough) */
+      style = CreateChildCSSNode(GTK_STYLE_CLASS_TROUGH, MOZ_GTK_PROGRESSBAR);
+      break;
+    case MOZ_GTK_PROGRESS_CHUNK:
+      style = CreateChildCSSNode("progress", MOZ_GTK_PROGRESS_TROUGH);
+      break;
+    case MOZ_GTK_GRIPPER:
+      // TODO - create from CSS node
+      style = CreateSubStyleWithClass(MOZ_GTK_GRIPPER, GTK_STYLE_CLASS_GRIP);
+      break;
+    case MOZ_GTK_SPINBUTTON_ENTRY:
+      // TODO - create from CSS node
+      style =
+          CreateSubStyleWithClass(MOZ_GTK_SPINBUTTON, GTK_STYLE_CLASS_ENTRY);
+      break;
+    case MOZ_GTK_SCROLLED_WINDOW:
+      // TODO - create from CSS node
+      style = CreateSubStyleWithClass(MOZ_GTK_SCROLLED_WINDOW,
+                                      GTK_STYLE_CLASS_FRAME);
+      break;
+    case MOZ_GTK_TEXT_VIEW_TEXT_SELECTION:
+      style = CreateChildCSSNode("selection", MOZ_GTK_TEXT_VIEW_TEXT);
+      break;
+    case MOZ_GTK_TEXT_VIEW_TEXT:
+    case MOZ_GTK_RESIZER:
+      style = CreateChildCSSNode("text", MOZ_GTK_TEXT_VIEW);
+      if (aNodeType == MOZ_GTK_RESIZER) {
+        // The "grip" class provides the correct builtin icon from
+        // gtk_render_handle().  The icon is drawn with shaded variants of
+        // the background color, and so a transparent background would lead to
+        // a transparent resizer.  gtk_render_handle() also uses the
+        // background color to draw a background, and so this style otherwise
+        // matches what is used in GtkTextView to match the background with
+        // textarea elements.
+        GdkRGBA color;
+        gtk_style_context_get_background_color(style, GTK_STATE_FLAG_NORMAL,
+                                               &color);
+        if (color.alpha == 0.0) {
+          g_object_unref(style);
+          style = CreateStyleForWidget(gtk_text_view_new(),
+                                       MOZ_GTK_SCROLLED_WINDOW);
+        }
+        gtk_style_context_add_class(style, GTK_STYLE_CLASS_GRIP);
+      }
+      break;
+    case MOZ_GTK_FRAME_BORDER:
+      style = CreateChildCSSNode("border", MOZ_GTK_FRAME);
+      break;
+    case MOZ_GTK_TREEVIEW_VIEW:
+      // TODO - create from CSS node
+      style = CreateSubStyleWithClass(MOZ_GTK_TREEVIEW, GTK_STYLE_CLASS_VIEW);
+      break;
+    case MOZ_GTK_TREEVIEW_EXPANDER:
+      // TODO - create from CSS node
+      style =
+          CreateSubStyleWithClass(MOZ_GTK_TREEVIEW, GTK_STYLE_CLASS_EXPANDER);
+      break;
+    case MOZ_GTK_SPLITTER_SEPARATOR_HORIZONTAL:
+      style = CreateChildCSSNode("separator", MOZ_GTK_SPLITTER_HORIZONTAL);
+      break;
+    case MOZ_GTK_SPLITTER_SEPARATOR_VERTICAL:
+      style = CreateChildCSSNode("separator", MOZ_GTK_SPLITTER_VERTICAL);
+      break;
+    case MOZ_GTK_SCALE_CONTENTS_HORIZONTAL:
+      style = CreateChildCSSNode("contents", MOZ_GTK_SCALE_HORIZONTAL);
+      break;
+    case MOZ_GTK_SCALE_CONTENTS_VERTICAL:
+      style = CreateChildCSSNode("contents", MOZ_GTK_SCALE_VERTICAL);
+      break;
+    case MOZ_GTK_SCALE_TROUGH_HORIZONTAL:
+      style = CreateChildCSSNode(GTK_STYLE_CLASS_TROUGH,
+                                 MOZ_GTK_SCALE_CONTENTS_HORIZONTAL);
+      break;
+    case MOZ_GTK_SCALE_TROUGH_VERTICAL:
+      style = CreateChildCSSNode(GTK_STYLE_CLASS_TROUGH,
+                                 MOZ_GTK_SCALE_CONTENTS_VERTICAL);
+      break;
+    case MOZ_GTK_SCALE_THUMB_HORIZONTAL:
+      style = CreateChildCSSNode(GTK_STYLE_CLASS_SLIDER,
+                                 MOZ_GTK_SCALE_TROUGH_HORIZONTAL);
+      break;
+    case MOZ_GTK_SCALE_THUMB_VERTICAL:
+      style = CreateChildCSSNode(GTK_STYLE_CLASS_SLIDER,
+                                 MOZ_GTK_SCALE_TROUGH_VERTICAL);
+      break;
+    case MOZ_GTK_TAB_TOP: {
+      // TODO - create from CSS node
+      style = CreateSubStyleWithClass(MOZ_GTK_NOTEBOOK, GTK_STYLE_CLASS_TOP);
+      gtk_style_context_add_region(style, GTK_STYLE_REGION_TAB,
+                                   static_cast<GtkRegionFlags>(0));
+      break;
+    }
+    case MOZ_GTK_TAB_BOTTOM: {
+      // TODO - create from CSS node
+      style = CreateSubStyleWithClass(MOZ_GTK_NOTEBOOK, GTK_STYLE_CLASS_BOTTOM);
+      gtk_style_context_add_region(style, GTK_STYLE_REGION_TAB,
+                                   static_cast<GtkRegionFlags>(0));
+      break;
+    }
+    case MOZ_GTK_NOTEBOOK:
+    case MOZ_GTK_NOTEBOOK_HEADER:
+    case MOZ_GTK_TABPANELS:
+    case MOZ_GTK_TAB_SCROLLARROW: {
+      // TODO - create from CSS node
+      GtkWidget* widget = GetWidget(MOZ_GTK_NOTEBOOK);
+      return gtk_widget_get_style_context(widget);
+    }
+    case MOZ_GTK_WINDOW_DECORATION: {
+      GtkStyleContext* parentStyle =
+          CreateSubStyleWithClass(MOZ_GTK_WINDOW, "csd");
+      style = CreateCSSNode("decoration", parentStyle);
+      g_object_unref(parentStyle);
+      break;
+    }
+    case MOZ_GTK_WINDOW_DECORATION_SOLID: {
+      GtkStyleContext* parentStyle =
+          CreateSubStyleWithClass(MOZ_GTK_WINDOW, "solid-csd");
+      style = CreateCSSNode("decoration", parentStyle);
+      g_object_unref(parentStyle);
+      break;
+    }
+    default:
+      return GetWidgetRootStyle(aNodeType);
+  }
+
+  MOZ_ASSERT(style, "missing style context for node type");
+  sStyleStorage[aNodeType] = style;
+  return style;
+}
+
+/* GetWidgetStyleInternal is used by Gtk < 3.20 */
+static GtkStyleContext* GetWidgetStyleInternal(WidgetNodeType aNodeType) {
+  GtkStyleContext* style = sStyleStorage[aNodeType];
+  if (style) return style;
+
+  switch (aNodeType) {
+    case MOZ_GTK_SCROLLBAR_TROUGH_VERTICAL:
+      style = CreateSubStyleWithClass(MOZ_GTK_SCROLLBAR_VERTICAL,
+                                      GTK_STYLE_CLASS_TROUGH);
+      break;
+    case MOZ_GTK_SCROLLBAR_THUMB_VERTICAL:
+      style = CreateSubStyleWithClass(MOZ_GTK_SCROLLBAR_VERTICAL,
+                                      GTK_STYLE_CLASS_SLIDER);
+      break;
+    case MOZ_GTK_RADIOBUTTON:
+      style = CreateSubStyleWithClass(MOZ_GTK_RADIOBUTTON_CONTAINER,
+                                      GTK_STYLE_CLASS_RADIO);
+      break;
+    case MOZ_GTK_CHECKBUTTON:
+      style = CreateSubStyleWithClass(MOZ_GTK_CHECKBUTTON_CONTAINER,
+                                      GTK_STYLE_CLASS_CHECK);
+      break;
+    case MOZ_GTK_PROGRESS_TROUGH:
+      style =
+          CreateSubStyleWithClass(MOZ_GTK_PROGRESSBAR, GTK_STYLE_CLASS_TROUGH);
+      break;
+    case MOZ_GTK_PROGRESS_CHUNK:
+      style = CreateSubStyleWithClass(MOZ_GTK_PROGRESSBAR,
+                                      GTK_STYLE_CLASS_PROGRESSBAR);
+      gtk_style_context_remove_class(style, GTK_STYLE_CLASS_TROUGH);
+      break;
+    case MOZ_GTK_GRIPPER:
+      style = CreateSubStyleWithClass(MOZ_GTK_GRIPPER, GTK_STYLE_CLASS_GRIP);
+      break;
+    case MOZ_GTK_SPINBUTTON_ENTRY:
+      style =
+          CreateSubStyleWithClass(MOZ_GTK_SPINBUTTON, GTK_STYLE_CLASS_ENTRY);
+      break;
+    case MOZ_GTK_SCROLLED_WINDOW:
+      style = CreateSubStyleWithClass(MOZ_GTK_SCROLLED_WINDOW,
+                                      GTK_STYLE_CLASS_FRAME);
+      break;
+    case MOZ_GTK_TEXT_VIEW_TEXT:
+    case MOZ_GTK_RESIZER:
+      // GTK versions prior to 3.20 do not have the view class on the root
+      // node, but add this to determine the background for the text window.
+      style = CreateSubStyleWithClass(MOZ_GTK_TEXT_VIEW, GTK_STYLE_CLASS_VIEW);
+      if (aNodeType == MOZ_GTK_RESIZER) {
+        // The "grip" class provides the correct builtin icon from
+        // gtk_render_handle().  The icon is drawn with shaded variants of
+        // the background color, and so a transparent background would lead to
+        // a transparent resizer.  gtk_render_handle() also uses the
+        // background color to draw a background, and so this style otherwise
+        // matches MOZ_GTK_TEXT_VIEW_TEXT to match the background with
+        // textarea elements.  GtkTextView creates a separate text window and
+        // so the background should not be transparent.
+        gtk_style_context_add_class(style, GTK_STYLE_CLASS_GRIP);
+      }
+      break;
+    case MOZ_GTK_FRAME_BORDER:
+      return GetWidgetRootStyle(MOZ_GTK_FRAME);
+    case MOZ_GTK_TREEVIEW_VIEW:
+      style = CreateSubStyleWithClass(MOZ_GTK_TREEVIEW, GTK_STYLE_CLASS_VIEW);
+      break;
+    case MOZ_GTK_TREEVIEW_EXPANDER:
+      style =
+          CreateSubStyleWithClass(MOZ_GTK_TREEVIEW, GTK_STYLE_CLASS_EXPANDER);
+      break;
+    case MOZ_GTK_SPLITTER_SEPARATOR_HORIZONTAL:
+      style = CreateSubStyleWithClass(MOZ_GTK_SPLITTER_HORIZONTAL,
+                                      GTK_STYLE_CLASS_PANE_SEPARATOR);
+      break;
+    case MOZ_GTK_SPLITTER_SEPARATOR_VERTICAL:
+      style = CreateSubStyleWithClass(MOZ_GTK_SPLITTER_VERTICAL,
+                                      GTK_STYLE_CLASS_PANE_SEPARATOR);
+      break;
+    case MOZ_GTK_SCALE_TROUGH_HORIZONTAL:
+      style = CreateSubStyleWithClass(MOZ_GTK_SCALE_HORIZONTAL,
+                                      GTK_STYLE_CLASS_TROUGH);
+      break;
+    case MOZ_GTK_SCALE_TROUGH_VERTICAL:
+      style = CreateSubStyleWithClass(MOZ_GTK_SCALE_VERTICAL,
+                                      GTK_STYLE_CLASS_TROUGH);
+      break;
+    case MOZ_GTK_SCALE_THUMB_HORIZONTAL:
+      style = CreateSubStyleWithClass(MOZ_GTK_SCALE_HORIZONTAL,
+                                      GTK_STYLE_CLASS_SLIDER);
+      break;
+    case MOZ_GTK_SCALE_THUMB_VERTICAL:
+      style = CreateSubStyleWithClass(MOZ_GTK_SCALE_VERTICAL,
+                                      GTK_STYLE_CLASS_SLIDER);
+      break;
+    case MOZ_GTK_TAB_TOP:
+      style = CreateSubStyleWithClass(MOZ_GTK_NOTEBOOK, GTK_STYLE_CLASS_TOP);
+      gtk_style_context_add_region(style, GTK_STYLE_REGION_TAB,
+                                   static_cast<GtkRegionFlags>(0));
+      break;
+    case MOZ_GTK_TAB_BOTTOM:
+      style = CreateSubStyleWithClass(MOZ_GTK_NOTEBOOK, GTK_STYLE_CLASS_BOTTOM);
+      gtk_style_context_add_region(style, GTK_STYLE_REGION_TAB,
+                                   static_cast<GtkRegionFlags>(0));
+      break;
+    case MOZ_GTK_NOTEBOOK:
+    case MOZ_GTK_NOTEBOOK_HEADER:
+    case MOZ_GTK_TABPANELS:
+    case MOZ_GTK_TAB_SCROLLARROW: {
+      GtkWidget* widget = GetWidget(MOZ_GTK_NOTEBOOK);
+      return gtk_widget_get_style_context(widget);
+    }
+    default:
+      return GetWidgetRootStyle(aNodeType);
+  }
+
+  MOZ_ASSERT(style);
+  sStyleStorage[aNodeType] = style;
+  return style;
+}
+
+void ResetWidgetCache() {
+  for (int i = 0; i < MOZ_GTK_WIDGET_NODE_COUNT; i++) {
+    if (sStyleStorage[i]) g_object_unref(sStyleStorage[i]);
+  }
+  mozilla::PodArrayZero(sStyleStorage);
+
+  gCSDStyle = CSDStyle::Unknown;
+
+  /* This will destroy all of our widgets */
+  if (sWidgetStorage[MOZ_GTK_WINDOW]) {
+    gtk_widget_destroy(sWidgetStorage[MOZ_GTK_WINDOW]);
+  }
+  if (sWidgetStorage[MOZ_GTK_HEADERBAR_WINDOW]) {
+    gtk_widget_destroy(sWidgetStorage[MOZ_GTK_HEADERBAR_WINDOW]);
+  }
+  if (sWidgetStorage[MOZ_GTK_HEADERBAR_WINDOW_MAXIMIZED]) {
+    gtk_widget_destroy(sWidgetStorage[MOZ_GTK_HEADERBAR_WINDOW_MAXIMIZED]);
+  }
+
+  /* Clear already freed arrays */
+  mozilla::PodArrayZero(sWidgetStorage);
+}
+
+GtkStyleContext* GetStyleContext(WidgetNodeType aNodeType, int aScale,
+                                 GtkTextDirection aDirection,
+                                 GtkStateFlags aStateFlags) {
+  GtkStyleContext* style;
+  if (gtk_check_version(3, 20, 0) != nullptr) {
+    style = GetWidgetStyleInternal(aNodeType);
+  } else {
+    style = GetCssNodeStyleInternal(aNodeType);
+    StyleContextSetScale(style, aScale);
+  }
+  bool stateChanged = false;
+  bool stateHasDirection = gtk_get_minor_version() >= 8;
+  GtkStateFlags oldState = gtk_style_context_get_state(style);
+  MOZ_ASSERT(!(aStateFlags & (STATE_FLAG_DIR_LTR | STATE_FLAG_DIR_RTL)));
+  unsigned newState = aStateFlags;
+  if (stateHasDirection) {
+    switch (aDirection) {
+      case GTK_TEXT_DIR_LTR:
+        newState |= STATE_FLAG_DIR_LTR;
+        break;
+      case GTK_TEXT_DIR_RTL:
+        newState |= STATE_FLAG_DIR_RTL;
+        break;
+      default:
+        MOZ_FALLTHROUGH_ASSERT("Bad GtkTextDirection");
+      case GTK_TEXT_DIR_NONE:
+        // GtkWidget uses a default direction if neither is explicitly
+        // specified, but here DIR_NONE is interpreted as meaning the
+        // direction is not important, so don't change the direction
+        // unnecessarily.
+        newState |= oldState & (STATE_FLAG_DIR_LTR | STATE_FLAG_DIR_RTL);
+    }
+  } else if (aDirection != GTK_TEXT_DIR_NONE) {
+    GtkTextDirection oldDirection = gtk_style_context_get_direction(style);
+    if (aDirection != oldDirection) {
+      gtk_style_context_set_direction(style, aDirection);
+      stateChanged = true;
+    }
+  }
+  if (oldState != newState) {
+    gtk_style_context_set_state(style, static_cast<GtkStateFlags>(newState));
+    stateChanged = true;
+  }
+  // This invalidate is necessary for unsaved style contexts from GtkWidgets
+  // in pre-3.18 GTK, because automatic invalidation of such contexts
+  // was delayed until a resize event runs.
+  //
+  // https://bugzilla.mozilla.org/show_bug.cgi?id=1272194#c7
+  //
+  // Avoid calling invalidate on contexts that are not owned and constructed
+  // by widgets to avoid performing build_properties() (in 3.16 stylecontext.c)
+  // unnecessarily early.
+  if (stateChanged && sWidgetStorage[aNodeType]) {
+    gtk_style_context_invalidate(style);
+  }
+  return style;
+}
+
+GtkStyleContext* CreateStyleContextWithStates(WidgetNodeType aNodeType,
+                                              int aScale,
+                                              GtkTextDirection aDirection,
+                                              GtkStateFlags aStateFlags) {
+  GtkStyleContext* style =
+      GetStyleContext(aNodeType, aScale, aDirection, aStateFlags);
+  GtkWidgetPath* path = gtk_widget_path_copy(gtk_style_context_get_path(style));
+
+  static auto sGtkWidgetPathIterGetState =
+      (GtkStateFlags(*)(const GtkWidgetPath*, gint))dlsym(
+          RTLD_DEFAULT, "gtk_widget_path_iter_get_state");
+  static auto sGtkWidgetPathIterSetState =
+      (void (*)(GtkWidgetPath*, gint, GtkStateFlags))dlsym(
+          RTLD_DEFAULT, "gtk_widget_path_iter_set_state");
+
+  int pathLength = gtk_widget_path_length(path);
+  for (int i = 0; i < pathLength; i++) {
+    unsigned state = aStateFlags | sGtkWidgetPathIterGetState(path, i);
+    sGtkWidgetPathIterSetState(path, i, GtkStateFlags(state));
+  }
+
+  style = gtk_style_context_new();
+  gtk_style_context_set_path(style, path);
+  gtk_widget_path_unref(path);
+
+  return style;
+}
+
+void StyleContextSetScale(GtkStyleContext* style, gint aScaleFactor) {
+  // Support HiDPI styles on Gtk 3.20+
+  static auto sGtkStyleContextSetScalePtr =
+      (void (*)(GtkStyleContext*, gint))dlsym(RTLD_DEFAULT,
+                                              "gtk_style_context_set_scale");
+  if (sGtkStyleContextSetScalePtr && style) {
+    sGtkStyleContextSetScalePtr(style, aScaleFactor);
+  }
+}
+
+bool HeaderBarShouldDrawContainer(WidgetNodeType aNodeType) {
+  MOZ_ASSERT(aNodeType == MOZ_GTK_HEADER_BAR ||
+             aNodeType == MOZ_GTK_HEADER_BAR_MAXIMIZED);
+  mozilla::Unused << GetWidget(aNodeType);
+  return aNodeType == MOZ_GTK_HEADER_BAR
+             ? gHeaderBarShouldDrawContainer
+             : gMaximizedHeaderBarShouldDrawContainer;
+}
+
+gint GetBorderRadius(GtkStyleContext* aStyle) {
+  GValue value = G_VALUE_INIT;
+  // NOTE(emilio): In an ideal world, we'd query the two longhands
+  // (border-top-left-radius and border-top-right-radius) separately. However,
+  // that doesn't work (GTK rejects the query with:
+  //
+  //   Style property "border-top-left-radius" is not gettable
+  //
+  // However! Getting border-radius does work, and it does return the
+  // border-top-left-radius as a gint:
+  //
+  //   https://docs.gtk.org/gtk3/const.STYLE_PROPERTY_BORDER_RADIUS.html
+  //   https://gitlab.gnome.org/GNOME/gtk/-/blob/gtk-3-20/gtk/gtkcssshorthandpropertyimpl.c#L961-977
+  //
+  // So we abuse this fact, and make the assumption here that the
+  // border-top-{left,right}-radius are the same, and roll with it.
+  gtk_style_context_get_property(aStyle, "border-radius", GTK_STATE_FLAG_NORMAL,
+                                 &value);
+  gint result = 0;
+  auto type = G_VALUE_TYPE(&value);
+  if (type == G_TYPE_INT) {
+    result = g_value_get_int(&value);
+  } else {
+    NS_WARNING(nsPrintfCString("Unknown value type %lu for border-radius", type)
+                   .get());
+  }
+  g_value_unset(&value);
+  return result;
+}