Bug 1736518 - Make browser.tabs.drawInTitlebar a tri-state. r=stransky,Gijs

To more properly support Linux having a different default at runtime.

Expose the resolved value in appinfo for convenience, and use it in the
front-end as needed.

Differential Revision: https://phabricator.services.mozilla.com/D129004

browser/app/profile/firefox.js

@@ -629,11 +629,6 @@ pref("browser.tabs.tabMinWidth", 76);
 // secondary text on tabs hidden due to size constraints and readability
 // of the text at small font sizes.
 pref("browser.tabs.secondaryTextUnsupportedLocales", "ar,bn,bo,ckb,fa,gu,he,hi,ja,km,kn,ko,lo,mr,my,ne,pa,si,ta,te,th,ur,zh");
-// Initial titlebar state is managed by -moz-gtk-csd-hide-titlebar-by-default
-// on Linux.
-#ifndef UNIX_BUT_NOT_MAC
-  pref("browser.tabs.drawInTitlebar", true);
-#endif
 
 //Control the visibility of Tab Manager Menu.
 pref("browser.tabs.tabmanager.enabled", false);

browser/base/content/browser-tabsintitlebar.js

@@ -54,10 +54,7 @@ var TabsInTitlebar = {
   _prefName: "browser.tabs.drawInTitlebar",
 
   _readPref() {
-    let hiddenTitlebar = Services.prefs.getBoolPref(
+    let hiddenTitlebar = Services.appinfo.drawInTitlebar;
-      "browser.tabs.drawInTitlebar",
-      window.matchMedia("(-moz-gtk-csd-hide-titlebar-by-default)").matches
-    );
     this.allowedBy("pref", hiddenTitlebar);
   },
 

browser/base/content/test/popups/browser_popupUI.js

@@ -61,8 +61,8 @@ add_task(async function titlebar_buttons_visibility() {
   Services.prefs.setIntPref("browser.link.open_newwindow", 2);
 
   const drawInTitlebarValues = [
-    [true, BUTTONS_MAY_VISIBLE],
+    [1, BUTTONS_MAY_VISIBLE],
-    [false, BUTTONS_NEVER_VISIBLE],
+    [0, BUTTONS_NEVER_VISIBLE],
   ];
   const windowFeaturesValues = [
     // Opens a popup
@@ -77,7 +77,7 @@ add_task(async function titlebar_buttons_visibility() {
   const menuBarShownValues = [true, false];
 
   for (const [drawInTitlebar, drawInTitlebarButtons] of drawInTitlebarValues) {
-    Services.prefs.setBoolPref("browser.tabs.drawInTitlebar", drawInTitlebar);
+    Services.prefs.setIntPref("browser.tabs.drawInTitlebar", drawInTitlebar);
 
     for (const [
       windowFeatures,

browser/base/content/test/startup/browser_preXULSkeletonUIRegistry.js

@@ -71,7 +71,7 @@ add_task(async function testWritesEnabledOnPrefChange() {
   is(enabled, 0, "Pre-XUL skeleton UI is disabled in the Windows registry");
 
   Services.prefs.setBoolPref("browser.startup.preXulSkeletonUI", true);
-  Services.prefs.setBoolPref("browser.tabs.drawInTitlebar", false);
+  Services.prefs.setIntPref("browser.tabs.drawInTitlebar", 0);
   enabled = WindowsRegistry.readRegKey(
     Ci.nsIWindowsRegKey.ROOT_KEY_CURRENT_USER,
     "Software\\Mozilla\\Firefox\\PreXULSkeletonUISettings",

browser/components/BrowserGlue.jsm

@@ -800,10 +800,7 @@ let JSWINDOWACTORS = {
   );
 
   // Hide the titlebar if the actual browser window will draw in it.
-  let hiddenTitlebar = Services.prefs.getBoolPref(
+  let hiddenTitlebar = Services.appinfo.drawInTitlebar;
-    "browser.tabs.drawInTitlebar",
-    win.matchMedia("(-moz-gtk-csd-hide-titlebar-by-default)").matches
-  );
   if (hiddenTitlebar) {
     win.windowUtils.setChromeMargin(0, 2, 2, 2);
   }

browser/components/customizableui/CustomizableUI.jsm

@@ -3151,12 +3151,8 @@ var CustomizableUIInternal = {
 
   _resetUIState() {
     try {
-      // kPrefDrawInTitlebar may not be defined on Linux/Gtk+ which throws an exception
+      gUIStateBeforeReset.drawInTitlebar = Services.prefs.getIntPref(
-      // and leads to whole test failure. Let's set a fallback default value to avoid that,
+        kPrefDrawInTitlebar
-      // both titlebar states are tested anyway and it's not important which state is tested first.
-      gUIStateBeforeReset.drawInTitlebar = Services.prefs.getBoolPref(
-        kPrefDrawInTitlebar,
-        false
       );
       gUIStateBeforeReset.uiCustomizationState = Services.prefs.getCharPref(
         kPrefCustomizationState
@@ -3246,7 +3242,7 @@ var CustomizableUIInternal = {
     this._clearPreviousUIState();
 
     Services.prefs.setCharPref(kPrefCustomizationState, uiCustomizationState);
-    Services.prefs.setBoolPref(kPrefDrawInTitlebar, drawInTitlebar);
+    Services.prefs.setIntPref(kPrefDrawInTitlebar, drawInTitlebar);
     Services.prefs.setIntPref(kPrefUIDensity, uiDensity);
     Services.prefs.setBoolPref(kPrefAutoTouchMode, autoTouchMode);
     Services.prefs.setBoolPref(

browser/components/customizableui/CustomizeMode.jsm

@@ -1715,10 +1715,7 @@ CustomizeMode.prototype = {
   },
 
   _updateTitlebarCheckbox() {
-    let drawInTitlebar = Services.prefs.getBoolPref(
+    let drawInTitlebar = Services.appinfo.drawInTitlebar;
-      kDrawInTitlebarPref,
-      this.window.matchMedia("(-moz-gtk-csd-hide-titlebar-by-default)").matches
-    );
     let checkbox = this.$("customization-titlebar-visibility-checkbox");
     // Drawing in the titlebar means 'hiding' the titlebar.
     // We use the attribute rather than a property because if we're not in
@@ -1732,7 +1729,7 @@ CustomizeMode.prototype = {
 
   toggleTitlebar(aShouldShowTitlebar) {
     // Drawing in the titlebar means not showing the titlebar, hence the negation:
-    Services.prefs.setBoolPref(kDrawInTitlebarPref, !aShouldShowTitlebar);
+    Services.prefs.setIntPref(kDrawInTitlebarPref, !aShouldShowTitlebar);
   },
 
   _getBoundsWithoutFlushing(element) {

browser/components/customizableui/test/browser_970511_undo_restore_default.js

@@ -142,11 +142,16 @@ add_task(async function() {
 
 // Bug 971626 - Restore Defaults should collapse the Title Bar
 add_task(async function() {
-  if (Services.appinfo.OS != "WINNT" && Services.appinfo.OS != "Darwin") {
+  {
-    return;
+    const supported = TabsInTitlebar.systemSupported;
+    is(typeof supported, "boolean");
+    info("TabsInTitlebar support: " + supported);
+    if (!supported) {
+      return;
+    }
   }
-  let prefName = "browser.tabs.drawInTitlebar";
+
-  let defaultValue = Services.prefs.getBoolPref(prefName);
+  const kDefaultValue = Services.appinfo.drawInTitlebar;
   let restoreDefaultsButton = document.getElementById(
     "customization-reset-button"
   );
@@ -166,7 +171,7 @@ add_task(async function() {
   );
   is(
     titlebarCheckbox.hasAttribute("checked"),
-    !defaultValue,
+    !kDefaultValue,
     "Title bar checkbox should reflect pref value"
   );
   is(
@@ -175,14 +180,20 @@ add_task(async function() {
     "Undo reset button should be hidden at start of test"
   );
 
-  Services.prefs.setBoolPref(prefName, !defaultValue);
+  let prefName = "browser.tabs.drawInTitlebar";
+  Services.prefs.setIntPref(prefName, !kDefaultValue);
   ok(
     !restoreDefaultsButton.disabled,
     "Restore defaults button should be enabled when pref changed"
   );
+  is(
+    Services.appinfo.drawInTitlebar,
+    !kDefaultValue,
+    "Title bar checkbox should reflect changed pref value"
+  );
   is(
     titlebarCheckbox.hasAttribute("checked"),
-    defaultValue,
+    kDefaultValue,
     "Title bar checkbox should reflect changed pref value"
   );
   ok(
@@ -202,14 +213,19 @@ add_task(async function() {
   );
   is(
     titlebarCheckbox.hasAttribute("checked"),
-    !defaultValue,
+    !kDefaultValue,
     "Title bar checkbox should reflect default value after reset"
   );
   is(
-    Services.prefs.getBoolPref(prefName),
+    Services.prefs.getIntPref(prefName),
-    defaultValue,
+    2,
     "Reset should reset drawInTitlebar"
   );
+  is(
+    Services.appinfo.drawInTitlebar,
+    kDefaultValue,
+    "Default state should be restored"
+  );
   ok(CustomizableUI.inDefaultState, "In default state after titlebar reset");
   is(
     undoResetButton.hidden,
@@ -228,13 +244,13 @@ add_task(async function() {
   );
   is(
     titlebarCheckbox.hasAttribute("checked"),
-    defaultValue,
+    kDefaultValue,
     "Title bar checkbox should reflect undo-reset value"
   );
   ok(!CustomizableUI.inDefaultState, "No longer in default state after undo");
   is(
-    Services.prefs.getBoolPref(prefName),
+    Services.prefs.getIntPref(prefName),
-    !defaultValue,
+    kDefaultValue ? 0 : 1,
     "Undo-reset goes back to previous pref value"
   );
   is(

browser/modules/BrowserUsageTelemetry.jsm

@@ -497,9 +497,7 @@ let BrowserUsageTelemetry = {
           case "browser.tabs.drawInTitlebar":
             this._recordWidgetChange(
               "titlebar",
-              Services.prefs.getBoolPref("browser.tabs.drawInTitlebar")
+              Services.appinfo.drawInTitlebar ? "off" : "on",
-                ? "off"
-                : "on",
               "pref"
             );
             break;
@@ -601,12 +599,7 @@ let BrowserUsageTelemetry = {
     widgetMap.set("menu-toolbar", menuBarHidden ? "off" : "on");
 
     // Drawing in the titlebar means not showing the titlebar, hence the negation.
-    widgetMap.set(
+    widgetMap.set("titlebar", Services.appinfo.drawInTitlebar ? "off" : "on");
-      "titlebar",
-      Services.prefs.getBoolPref("browser.tabs.drawInTitlebar", true)
-        ? "off"
-        : "on"
-    );
 
     for (let area of CustomizableUI.areas) {
       if (!(area in BROWSER_UI_CONTAINER_IDS)) {

browser/modules/test/browser/browser_UsageTelemetry_toolbars.js

@@ -111,7 +111,7 @@ function organizeToolbars(state = {}) {
     targetState.personalToolbarVisible
   );
 
-  Services.prefs.setBoolPref(
+  Services.prefs.setIntPref(
     "browser.tabs.drawInTitlebar",
     !targetState.titlebarVisible
   );

browser/tools/mozscreenshots/mozscreenshots/extension/configurations/TabsInTitlebar.jsm

@@ -17,10 +17,7 @@ var TabsInTitlebar = {
     tabsInTitlebar: {
       selectors: ["#navigator-toolbox"],
       async applyConfig() {
-        if (Services.appinfo.OS == "Linux") {
+        Services.prefs.setIntPref(PREF_TABS_IN_TITLEBAR, 1);
-          return "TabsInTitlebar isn't supported on Linux";
-        }
-        Services.prefs.setBoolPref(PREF_TABS_IN_TITLEBAR, true);
         return undefined;
       },
     },
@@ -30,7 +27,7 @@ var TabsInTitlebar = {
         Services.appinfo.OS == "Linux" ? [] : ["#titlebar"]
       ),
       async applyConfig() {
-        Services.prefs.setBoolPref(PREF_TABS_IN_TITLEBAR, false);
+        Services.prefs.setIntPref(PREF_TABS_IN_TITLEBAR, 0);
       },
     },
   },

layout/style/test/chrome/bug418986-2.js

@@ -61,7 +61,6 @@ var suppressed_toggles = [
   "-moz-windows-default-theme",
   "-moz-windows-glass",
   "-moz-gtk-csd-available",
-  "-moz-gtk-csd-hide-titlebar-by-default",
   "-moz-gtk-csd-minimize-button",
   "-moz-gtk-csd-maximize-button",
   "-moz-gtk-csd-close-button",

layout/style/test/chrome/chrome-only-media-queries.js

@@ -21,7 +21,6 @@ const CHROME_ONLY_TOGGLES = [
   "-moz-windows-non-native-menus",
   "-moz-swipe-animation-enabled",
   "-moz-gtk-csd-available",
-  "-moz-gtk-csd-hide-titlebar-by-default",
   "-moz-gtk-csd-minimize-button",
   "-moz-gtk-csd-maximize-button",
   "-moz-gtk-csd-close-button",

modules/libpref/init/StaticPrefList.yaml

@@ -1300,6 +1300,14 @@
   value: false
   mirror: always
 
+# Whether we should draw the tabs on top of the titlebar.
+#
+# no (0), yes (1), or default (2), which is true everywhere except Linux.
+- name: browser.tabs.drawInTitlebar
+  type: int32_t
+  value: 2
+  mirror: always
+
 # If set, use DocumentChannel to directly initiate loads entirely
 # from parent-process BrowsingContexts
 - name: browser.tabs.documentchannel.parent-controlled

servo/components/style/gecko/media_features.rs

@@ -651,7 +651,7 @@ macro_rules! bool_pref_feature {
 /// to support new types in these entries and (2) ensuring that either
 /// nsPresContext::MediaFeatureValuesChanged is called when the value that
 /// would be returned by the evaluator function could change.
-pub static MEDIA_FEATURES: [MediaFeatureDescription; 59] = [
+pub static MEDIA_FEATURES: [MediaFeatureDescription; 58] = [
     feature!(
         atom!("width"),
         AllowsRanges::Yes,
@@ -890,7 +890,6 @@ pub static MEDIA_FEATURES: [MediaFeatureDescription; 59] = [
     lnf_int_feature!(atom!("-moz-windows-glass"), WindowsGlass),
     lnf_int_feature!(atom!("-moz-swipe-animation-enabled"), SwipeAnimationEnabled),
     lnf_int_feature!(atom!("-moz-gtk-csd-available"), GTKCSDAvailable),
-    lnf_int_feature!(atom!("-moz-gtk-csd-hide-titlebar-by-default"), GTKCSDHideTitlebarByDefault),
     lnf_int_feature!(atom!("-moz-gtk-csd-minimize-button"), GTKCSDMinimizeButton),
     lnf_int_feature!(atom!("-moz-gtk-csd-maximize-button"), GTKCSDMaximizeButton),
     lnf_int_feature!(atom!("-moz-gtk-csd-close-button"), GTKCSDCloseButton),

toolkit/xre/nsAppRunner.cpp

@@ -23,6 +23,7 @@
 #include "mozilla/Printf.h"
 #include "mozilla/ResultExtensions.h"
 #include "mozilla/ScopeExit.h"
+#include "mozilla/StaticPrefs_browser.h"
 #include "mozilla/StaticPrefs_fission.h"
 #include "mozilla/Telemetry.h"
 #include "mozilla/Utf8.h"
@@ -276,7 +277,6 @@ static const char kPrefThemeId[] = "extensions.activeThemeID";
 static const char kPrefBrowserStartupBlankWindow[] =
     "browser.startup.blankWindow";
 static const char kPrefPreXulSkeletonUI[] = "browser.startup.preXulSkeletonUI";
-static const char kPrefDrawTabsInTitlebar[] = "browser.tabs.drawInTitlebar";
 #endif  // defined(XP_WIN)
 
 int gArgc;
@@ -1331,6 +1331,12 @@ nsXULAppInfo::GetChromeColorSchemeIsDark(bool* aResult) {
   return NS_OK;
 }
 
+NS_IMETHODIMP
+nsXULAppInfo::GetDrawInTitlebar(bool* aResult) {
+  *aResult = LookAndFeel::DrawInTitlebar();
+  return NS_OK;
+}
+
 NS_IMETHODIMP
 nsXULAppInfo::GetProcessStartupShortcut(nsAString& aShortcut) {
 #if defined(XP_WIN)
@@ -1996,7 +2002,7 @@ static void ReflectSkeletonUIPrefToRegistry(const char* aPref, void* aData) {
   bool shouldBeEnabled =
       Preferences::GetBool(kPrefPreXulSkeletonUI, false) &&
       Preferences::GetBool(kPrefBrowserStartupBlankWindow, false) &&
-      Preferences::GetBool(kPrefDrawTabsInTitlebar, false);
+      LookAndFeel::DrawInTitlebar();
   if (shouldBeEnabled && Preferences::HasUserValue(kPrefThemeId)) {
     nsCString themeId;
     Preferences::GetCString(kPrefThemeId, themeId);
@@ -2025,8 +2031,9 @@ static void SetupSkeletonUIPrefs() {
   Preferences::RegisterCallback(&ReflectSkeletonUIPrefToRegistry,
                                 kPrefBrowserStartupBlankWindow);
   Preferences::RegisterCallback(&ReflectSkeletonUIPrefToRegistry, kPrefThemeId);
-  Preferences::RegisterCallback(&ReflectSkeletonUIPrefToRegistry,
+  Preferences::RegisterCallback(
-                                kPrefDrawTabsInTitlebar);
+      &ReflectSkeletonUIPrefToRegistry,
+      nsDependentCString(StaticPrefs::GetPrefName_browser_tabs_drawInTitlebar()));
 }
 
 #  if defined(MOZ_LAUNCHER_PROCESS)

widget/LookAndFeel.h

@@ -246,12 +246,6 @@ class LookAndFeel {
      */
     GTKCSDAvailable,
 
-    /*
-     * A boolean value indicating whether GTK+ system titlebar should be
-     * disabled by default.
-     */
-    GTKCSDHideTitlebarByDefault,
-
     /*
      * A boolean value indicating whether client-side decorations should
      * contain a minimize button.
@@ -509,6 +503,11 @@ class LookAndFeel {
    */
   static bool GetEchoPassword();
 
+  /**
+   * Whether we should be drawing in the titlebar by default.
+   */
+  static bool DrawInTitlebar();
+
   /**
    * The millisecond to mask password value.
    * This value is only valid when GetEchoPassword() returns true.

widget/gtk/nsLookAndFeel.cpp

@@ -789,10 +789,6 @@ nsresult nsLookAndFeel::NativeGetInt(IntID aID, int32_t& aResult) {
       EnsureInit();
       aResult = mCSDAvailable;
       break;
-    case IntID::GTKCSDHideTitlebarByDefault:
-      EnsureInit();
-      aResult = mCSDHideTitlebarByDefault;
-      break;
     case IntID::GTKCSDMaximizeButton:
       EnsureInit();
       aResult = mCSDMaximizeButton;
@@ -1246,7 +1242,6 @@ void nsLookAndFeel::EnsureInit() {
 
   mCSDAvailable =
       nsWindow::GtkWindowDecoration() != nsWindow::GTK_DECORATION_NONE;
-  mCSDHideTitlebarByDefault = nsWindow::HideTitlebarByDefault();
 
   mSystemTheme.Init();
 
@@ -1840,6 +1835,29 @@ char16_t nsLookAndFeel::GetPasswordCharacterImpl() {
 
 bool nsLookAndFeel::GetEchoPasswordImpl() { return false; }
 
+bool nsLookAndFeel::GetDefaultDrawInTitlebar() {
+  static bool drawInTitlebar = []() {
+    // When user defined widget.default-hidden-titlebar don't do any
+    // heuristics and just follow it.
+    if (Preferences::HasUserValue("widget.default-hidden-titlebar")) {
+      return Preferences::GetBool("widget.default-hidden-titlebar", false);
+    }
+
+    // Don't hide titlebar when it's disabled on current desktop.
+    const char* currentDesktop = getenv("XDG_CURRENT_DESKTOP");
+    if (!currentDesktop || nsWindow::GetSystemGtkWindowDecoration() ==
+                               nsWindow::GTK_DECORATION_NONE) {
+      return false;
+    }
+
+    // We hide system titlebar on Gnome/ElementaryOS without any restriction.
+    return strstr(currentDesktop, "GNOME-Flashback:GNOME") ||
+           strstr(currentDesktop, "GNOME") ||
+           strstr(currentDesktop, "Pantheon");
+  }();
+  return drawInTitlebar;
+}
+
 void nsLookAndFeel::GetThemeInfo(nsACString& aInfo) {
   aInfo.Append(mSystemTheme.mName);
   aInfo.Append(" / ");

widget/gtk/nsLookAndFeel.h

@@ -32,6 +32,8 @@ class nsLookAndFeel final : public nsXPLookAndFeel {
   char16_t GetPasswordCharacterImpl() override;
   bool GetEchoPasswordImpl() override;
 
+  bool GetDefaultDrawInTitlebar() override;
+
   template <typename Callback>
   void WithAltThemeConfigured(const Callback&);
 
@@ -155,7 +157,6 @@ class nsLookAndFeel final : public nsXPLookAndFeel {
   int32_t mCaretBlinkTime = 0;
   int32_t mCaretBlinkCount = -1;
   bool mCSDAvailable = false;
-  bool mCSDHideTitlebarByDefault = false;
   bool mCSDMaximizeButton = false;
   bool mCSDMinimizeButton = false;
   bool mCSDCloseButton = false;

widget/gtk/nsWindow.cpp

@@ -8720,29 +8720,6 @@ bool nsWindow::TitlebarUseShapeMask() {
   return useShapeMask;
 }
 
-bool nsWindow::HideTitlebarByDefault() {
-  static int hideTitlebar = []() {
-    // When user defined widget.default-hidden-titlebar don't do any
-    // heuristics and just follow it.
-    if (Preferences::HasUserValue("widget.default-hidden-titlebar")) {
-      return Preferences::GetBool("widget.default-hidden-titlebar", false);
-    }
-
-    // Don't hide titlebar when it's disabled on current desktop.
-    const char* currentDesktop = getenv("XDG_CURRENT_DESKTOP");
-    if (!currentDesktop ||
-        GetSystemGtkWindowDecoration() == GTK_DECORATION_NONE) {
-      return false;
-    }
-
-    // We hide system titlebar on Gnome/ElementaryOS without any restriction.
-    return ((strstr(currentDesktop, "GNOME-Flashback:GNOME") != nullptr ||
-             strstr(currentDesktop, "GNOME") != nullptr ||
-             strstr(currentDesktop, "Pantheon") != nullptr));
-  }();
-  return hideTitlebar;
-}
-
 int32_t nsWindow::RoundsWidgetCoordinatesTo() { return GdkCeiledScaleFactor(); }
 
 void nsWindow::GetCompositorWidgetInitData(

widget/gtk/nsWindow.h

@@ -367,7 +367,6 @@ class nsWindow final : public nsBaseWidget {
    */
   static GtkWindowDecoration GetSystemGtkWindowDecoration();
 
-  static bool HideTitlebarByDefault();
   static bool GetTopLevelWindowActiveState(nsIFrame* aFrame);
   static bool TitlebarUseShapeMask();
   bool IsRemoteContent() { return HasRemoteContent(); }

widget/headless/HeadlessLookAndFeelGTK.cpp

@@ -256,7 +256,6 @@ nsresult HeadlessLookAndFeel::NativeGetInt(IntID aID, int32_t& aResult) {
       aResult = 1;
       break;
     case IntID::GTKCSDAvailable:
-    case IntID::GTKCSDHideTitlebarByDefault:
       aResult = 0;
       break;
     case IntID::GTKCSDMinimizeButton:

widget/nsXPLookAndFeel.cpp

@@ -160,7 +160,6 @@ static const char sIntPrefs[][43] = {
     "ui.contextMenuOffsetVertical",
     "ui.contextMenuOffsetHorizontal",
     "ui.GtkCSDAvailable",
-    "ui.GtkCSDHideTitlebarByDefault",
     "ui.GtkCSDMinimizeButton",
     "ui.GtkCSDMaximizeButton",
     "ui.GtkCSDCloseButton",
@@ -1266,6 +1265,18 @@ uint32_t LookAndFeel::GetPasswordMaskDelay() {
   return delay;
 }
 
+bool LookAndFeel::DrawInTitlebar() {
+  switch (StaticPrefs::browser_tabs_drawInTitlebar()) {
+    case 0:
+      return false;
+    case 1:
+      return true;
+    default:
+      break;
+  }
+  return nsLookAndFeel::GetInstance()->GetDefaultDrawInTitlebar();
+}
+
 void LookAndFeel::GetThemeInfo(nsACString& aOut) {
   nsLookAndFeel::GetInstance()->GetThemeInfo(aOut);
 }

widget/nsXPLookAndFeel.h

@@ -56,6 +56,8 @@ class nsXPLookAndFeel : public mozilla::LookAndFeel {
 
   virtual uint32_t GetPasswordMaskDelayImpl() { return 600; }
 
+  virtual bool GetDefaultDrawInTitlebar() { return true; }
+
   static bool LookAndFeelFontToStyle(const LookAndFeelFont&, nsString& aName,
                                      gfxFontStyle&);
   static LookAndFeelFont StyleToLookAndFeelFont(const nsAString& aName,

xpcom/ds/StaticAtoms.py

@@ -2225,7 +2225,6 @@ STATIC_ATOMS = [
     Atom("_moz_is_resource_document", "-moz-is-resource-document"),
     Atom("_moz_swipe_animation_enabled", "-moz-swipe-animation-enabled"),
     Atom("_moz_gtk_csd_available", "-moz-gtk-csd-available"),
-    Atom("_moz_gtk_csd_hide_titlebar_by_default", "-moz-gtk-csd-hide-titlebar-by-default"),
     Atom("_moz_gtk_csd_titlebar_radius", "-moz-gtk-csd-titlebar-radius"),
     Atom("_moz_gtk_csd_minimize_button", "-moz-gtk-csd-minimize-button"),
     Atom("_moz_gtk_csd_maximize_button", "-moz-gtk-csd-maximize-button"),

xpcom/system/nsIXULRuntime.idl

@@ -319,6 +319,9 @@ interface nsIXULRuntime : nsISupports
   /** Whether the chrome color-scheme is dark */
   readonly attribute boolean chromeColorSchemeIsDark;
 
+  /** Whether we should draw over the titlebar */
+  readonly attribute boolean drawInTitlebar;
+
   /**
    * The path of the shortcut used to start the current process, or "" if none.
    *