deleted file mode 100644
--- a/browser/base/content/browser-tabsintitlebar-stub.js
+++ /dev/null
@@ -1,16 +0,0 @@
-/* -*- indent-tabs-mode: nil; js-indent-level: 2 -*-
- * This Source Code Form is subject to the terms of the Mozilla Public
- * License, v. 2.0. If a copy of the MPL was not distributed with this
- * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
-
-// This file is used as a stub object for platforms which
-// don't have CAN_DRAW_IN_TITLEBAR defined.
-
-var TabsInTitlebar = {
-  init() {},
-  whenWindowLayoutReady() {},
-  uninit() {},
-  allowedBy() {},
-  update() {},
-  enabled: false,
-};

--- a/browser/base/content/browser-tabsintitlebar.js
+++ b/browser/base/content/browser-tabsintitlebar.js
@@ -1,26 +1,18 @@
 /* -*- indent-tabs-mode: nil; js-indent-level: 2 -*-
  * This Source Code Form is subject to the terms of the Mozilla Public
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
-// Note: the file browser-tabsintitlebar-stub.js is used instead of
-// this one on platforms which don't have CAN_DRAW_IN_TITLEBAR defined.
-
 var TabsInTitlebar = {
   init() {
     this._readPref();
     Services.prefs.addObserver(this._prefName, this);
 
-    // Always disable on unsupported GTK versions.
-    if (AppConstants.MOZ_WIDGET_TOOLKIT == "gtk3") {
-      this.allowedBy("gtk", window.matchMedia("(-moz-gtk-csd-available)"));
-    }
-
     // We need to update the appearance of the titlebar when the menu changes
     // from the active to the inactive state. We can't, however, rely on
     // DOMMenuBarInactive, because the menu fires this event and then removes
     // the inactive attribute after an event-loop spin.
     //
     // Because updating the appearance involves sampling the heights and margins
     // of various elements, it's important that the layout be more or less
     // settled before updating the titlebar. So instead of listening to
@@ -61,16 +53,31 @@ var TabsInTitlebar = {
         this.update();
       }
     } else if (!(condition in this._disallowed)) {
       this._disallowed[condition] = null;
       this.update();
     }
   },
 
+  get systemSupported() {
+    let isSupported = false;
+    switch (AppConstants.MOZ_WIDGET_TOOLKIT) {
+      case "windows":
+      case "cocoa":
+        isSupported = true;
+        break;
+      case "gtk3":
+        isSupported = window.matchMedia("(-moz-gtk-csd-available)");
+        break;
+    }
+    delete this.systemSupported;
+    return this.systemSupported = isSupported;
+  },
+
   get enabled() {
     return document.documentElement.getAttribute("tabsintitlebar") == "true";
   },
 
   observe(subject, topic, data) {
     if (topic == "nsPref:changed")
       this._readPref();
   },
@@ -129,17 +136,18 @@ var TabsInTitlebar = {
                    Services.prefs.getBoolPref(this._prefName));
   },
 
   update() {
     if (!this._initialized || window.fullScreen) {
       return;
     }
 
-    let allowed = (Object.keys(this._disallowed)).length == 0;
+    let allowed = this.systemSupported &&
+                  (Object.keys(this._disallowed)).length == 0;
     if (allowed) {
       document.documentElement.setAttribute("tabsintitlebar", "true");
       if (AppConstants.platform == "macosx") {
         document.documentElement.setAttribute("chromemargin", "0,-1,-1,-1");
         document.documentElement.removeAttribute("drawtitle");
       } else {
         document.documentElement.setAttribute("chromemargin", "0,2,2,2");
       }

--- a/browser/base/content/browser.css
+++ b/browser/base/content/browser.css
@@ -272,17 +272,16 @@ window:not([chromehidden~="toolbar"]) #n
  * using a tagname as the last item would be less so.
  */
 #widget-overflow-list:empty + #widget-overflow-fixed-separator,
 #widget-overflow:not([hasfixeditems]) #widget-overflow-fixed-separator {
   display: none;
 }
 
 
-%ifdef CAN_DRAW_IN_TITLEBAR
 %ifdef MENUBAR_CAN_AUTOHIDE
 #toolbar-menubar:not([autohide=true]) + #TabsToolbar > .titlebar-placeholder,
 %endif
 %ifndef MOZ_WIDGET_COCOA
 #main-window:not([sizemode=normal]) .titlebar-placeholder[type="pre-tabs"],
 %endif
 #main-window:not([chromemargin]) > #titlebar,
 #main-window[inFullscreen] > #titlebar,
@@ -342,18 +341,16 @@ toolbarpaletteitem {
 }
 
 #main-window[tabletmode] #titlebar-min,
 #main-window[tabletmode] #titlebar-max {
   display: none !important;
 }
 %endif
 
-%endif
-
 #main-window[inFullscreen][inDOMFullscreen] #navigator-toolbox,
 #main-window[inFullscreen][inDOMFullscreen] #fullscr-toggler,
 #main-window[inFullscreen][inDOMFullscreen] #sidebar-box,
 #main-window[inFullscreen][inDOMFullscreen] #sidebar-splitter,
 #main-window[inFullscreen][inDOMFullscreen] #developer-toolbar,
 #main-window[inFullscreen]:not([OSXLionFullscreen]) toolbar:not([fullscreentoolbar=true]),
 #main-window[inFullscreen] #global-notificationbox,
 #main-window[inFullscreen] #high-priority-global-notificationbox {

--- a/browser/base/content/browser.xul
+++ b/browser/base/content/browser.xul
@@ -41,24 +41,22 @@
         titlemodifier_normal=""
         titlemodifier_privatebrowsing="&mainWindow.titlePrivateBrowsingSuffix;"
 #else
         title_privatebrowsing="&mainWindow.titlemodifier; &mainWindow.titlePrivateBrowsingSuffix;"
         titlemodifier="&mainWindow.titlemodifier;"
         titlemodifier_normal="&mainWindow.titlemodifier;"
         titlemodifier_privatebrowsing="&mainWindow.titlemodifier; &mainWindow.titlePrivateBrowsingSuffix;"
 #endif
-#ifdef CAN_DRAW_IN_TITLEBAR
 #ifdef XP_WIN
         chromemargin="0,2,2,2"
 #else
         chromemargin="0,-1,-1,-1"
 #endif
         tabsintitlebar="true"
-#endif
         titlemenuseparator="&mainWindow.titlemodifiermenuseparator;"
         windowtype="navigator:browser"
         macanimationtype="document"
         screenX="4" screenY="4"
         fullscreenbutton="true"
         sizemode="normal"
         retargetdocumentfocus="urlbar"
         persist="screenX screenY width height sizemode">
@@ -593,17 +591,16 @@
       <menuseparator/>
       <menuitem label="&syncSyncNowItem.label;"
                 accesskey="&syncSyncNowItem.accesskey;"
                 id="syncedTabsRefreshFilter"/>
     </menupopup>
   </popupset>
   <box id="appMenu-viewCache" hidden="true"/>
 
-#ifdef CAN_DRAW_IN_TITLEBAR
 <vbox id="titlebar">
   <hbox id="titlebar-content">
     <spacer id="titlebar-spacer" flex="1"/>
     <hbox id="titlebar-buttonbox-container">
       <hbox id="titlebar-buttonbox" class="titlebar-color">
         <toolbarbutton class="titlebar-button" id="titlebar-min" oncommand="window.minimize();"/>
         <toolbarbutton class="titlebar-button" id="titlebar-max" oncommand="onTitlebarMaxClick();"/>
         <toolbarbutton class="titlebar-button" id="titlebar-close" command="cmd_closeWindow"/>
@@ -615,17 +612,16 @@
     <hbox id="titlebar-secondary-buttonbox" dir="ltr">
       <button class="accessibility-indicator" tooltiptext="&accessibilityIndicator.tooltip;" aria-live="polite"/>
       <hbox class="private-browsing-indicator"/>
       <hbox id="titlebar-fullscreen-button"/>
     </hbox>
 #endif
   </hbox>
 </vbox>
-#endif
 
   <toolbox id="navigator-toolbox">
     <!-- Menu -->
     <toolbar type="menubar" id="toolbar-menubar"
              class="chromeclass-menubar titlebar-color"
              customizable="true"
              mode="icons"
 #ifdef MENUBAR_CAN_AUTOHIDE
@@ -635,37 +631,32 @@
 #endif
              context="toolbar-context-menu">
       <toolbaritem id="menubar-items" align="center">
 # The entire main menubar is placed into browser-menubar.inc, so that it can be
 # shared with other top level windows in macWindow.inc.xul.
 #include browser-menubar.inc
       </toolbaritem>
 
-#ifdef CAN_DRAW_IN_TITLEBAR
 #ifndef XP_MACOSX
       <hbox class="titlebar-placeholder" type="caption-buttons" ordinal="1000"
             skipintoolbarset="true"/>
 #endif
-#endif
     </toolbar>
 
     <toolbar id="TabsToolbar"
              class="titlebar-color"
              fullscreentoolbar="true"
              customizable="true"
              mode="icons"
              aria-label="&tabsToolbar.label;"
              context="toolbar-context-menu"
              collapsed="true">
-
-#ifdef CAN_DRAW_IN_TITLEBAR
       <hbox class="titlebar-placeholder" type="pre-tabs"
             skipintoolbarset="true"/>
-#endif
 
       <tabs id="tabbrowser-tabs"
             flex="1"
             setfocus="false"
             tooltip="tabbrowser-tab-tooltip"
             stopwatchid="FX_TAB_CLICK_MS">
         <tab class="tabbrowser-tab" selected="true" visuallyselected="true" fadein="true"/>
       </tabs>
@@ -699,39 +690,35 @@
           <menu id="alltabs_containersTab"
                 label="&newUserContext.label;">
             <menupopup id="alltabs_containersMenuTab" />
           </menu>
           <menuseparator id="alltabs-popup-separator-2"/>
         </menupopup>
       </toolbarbutton>
 
-#ifdef CAN_DRAW_IN_TITLEBAR
       <hbox class="titlebar-placeholder" type="post-tabs"
             ordinal="1000"
             skipintoolbarset="true"/>
-#endif
 
       <button class="accessibility-indicator" tooltiptext="&accessibilityIndicator.tooltip;"
               ordinal="1000"
               aria-live="polite" skipintoolbarset="true"/>
       <hbox class="private-browsing-indicator" skipintoolbarset="true"
             ordinal="1000"/>
-#ifdef CAN_DRAW_IN_TITLEBAR
       <hbox class="titlebar-placeholder" type="caption-buttons"
 #ifndef XP_MACOSX
             ordinal="1000"
 #endif
             skipintoolbarset="true"/>
 
 #ifdef XP_MACOSX
       <hbox class="titlebar-placeholder" type="fullscreen-button"
             skipintoolbarset="true"/>
 #endif
-#endif
     </toolbar>
 
     <toolbar id="nav-bar"
              aria-label="&navbarCmd.label;"
              fullscreentoolbar="true" mode="icons" customizable="true"
              customizationtarget="nav-bar-customization-target"
              overflowable="true"
              overflowbutton="nav-bar-overflow-button"

--- a/browser/base/jar.mn
+++ b/browser/base/jar.mn
@@ -63,21 +63,17 @@ browser.jar:
         content/browser/browser-media.js              (content/browser-media.js)
         content/browser/browser-pageActions.js        (content/browser-pageActions.js)
         content/browser/browser-places.js             (content/browser-places.js)
         content/browser/browser-plugins.js            (content/browser-plugins.js)
         content/browser/browser-safebrowsing.js       (content/browser-safebrowsing.js)
         content/browser/browser-sidebar.js            (content/browser-sidebar.js)
         content/browser/browser-sync.js               (content/browser-sync.js)
 *       content/browser/browser-tabPreviews.xml       (content/browser-tabPreviews.xml)
-#ifdef CAN_DRAW_IN_TITLEBAR
         content/browser/browser-tabsintitlebar.js       (content/browser-tabsintitlebar.js)
-#else
-        content/browser/browser-tabsintitlebar.js       (content/browser-tabsintitlebar-stub.js)
-#endif
         content/browser/browser-thumbnails.js         (content/browser-thumbnails.js)
         content/browser/browser-trackingprotection.js (content/browser-trackingprotection.js)
         content/browser/browser-webrender.js          (content/browser-webrender.js)
         content/browser/tab-content.js                (content/tab-content.js)
         content/browser/content.js                    (content/content.js)
         content/browser/default-theme-icon.svg        (content/default-theme-icon.svg)
         content/browser/defaultthemes/1.header.jpg    (content/defaultthemes/1.header.jpg)
         content/browser/defaultthemes/1.icon.jpg      (content/defaultthemes/1.icon.jpg)

--- a/browser/base/moz.build
+++ b/browser/base/moz.build
@@ -57,15 +57,12 @@ BROWSER_CHROME_MANIFESTS += [
 DEFINES['MOZ_APP_VERSION'] = CONFIG['MOZ_APP_VERSION']
 DEFINES['MOZ_APP_VERSION_DISPLAY'] = CONFIG['MOZ_APP_VERSION_DISPLAY']
 
 DEFINES['APP_LICENSE_BLOCK'] = '%s/content/overrides/app-license.html' % SRCDIR
 
 if CONFIG['MOZ_WIDGET_TOOLKIT'] in ('windows', 'gtk3', 'cocoa'):
     DEFINES['CONTEXT_COPY_IMAGE_CONTENTS'] = 1
 
-if CONFIG['MOZ_WIDGET_TOOLKIT'] in ('windows', 'cocoa', 'gtk3'):
-    DEFINES['CAN_DRAW_IN_TITLEBAR'] = 1
-
 if CONFIG['MOZ_WIDGET_TOOLKIT'] in ('windows', 'gtk3'):
     DEFINES['MENUBAR_CAN_AUTOHIDE'] = 1
 
 JAR_MANIFESTS += ['jar.mn']

--- a/browser/components/customizableui/CustomizeMode.jsm
+++ b/browser/components/customizableui/CustomizeMode.jsm
@@ -97,24 +97,29 @@ function CustomizeMode(aWindow) {
   this.document = aWindow.document;
   this.browser = aWindow.gBrowser;
   this.areas = new Set();
 
   // There are two palettes - there's the palette that can be overlayed with
   // toolbar items in browser.xul. This is invisible, and never seen by the
   // user. Then there's the visible palette, which gets populated and displayed
   // to the user when in customizing mode.
-  this.visiblePalette = this.document.getElementById(kPaletteId);
-  this.pongArena = this.document.getElementById("customization-pong-arena");
-  if (AppConstants.CAN_DRAW_IN_TITLEBAR) {
+  this.visiblePalette = this.$(kPaletteId);
+  this.pongArena = this.$("customization-pong-arena");
+
+  if (this._canDrawInTitlebar()) {
     this._updateTitlebarCheckbox();
     this._updateDragSpaceCheckbox();
     Services.prefs.addObserver(kDrawInTitlebarPref, this);
     Services.prefs.addObserver(kExtraDragSpacePref, this);
+  } else {
+    this.$("customization-titlebar-visibility-checkbox").hidden = true;
+    this.$("customization-extra-drag-space-checkbox").hidden = true;
   }
+
   this.window.addEventListener("unload", this);
 }
 
 CustomizeMode.prototype = {
   _changed: false,
   _transitioning: false,
   window: null,
   document: null,
@@ -133,22 +138,26 @@ CustomizeMode.prototype = {
   _skipSourceNodeCheck: null,
   _mainViewContext: null,
 
   get _handler() {
     return this.window.CustomizationHandler;
   },
 
   uninit() {
-    if (AppConstants.CAN_DRAW_IN_TITLEBAR) {
+    if (this._canDrawInTitlebar()) {
       Services.prefs.removeObserver(kDrawInTitlebarPref, this);
       Services.prefs.removeObserver(kExtraDragSpacePref, this);
     }
   },
 
+  $(id) {
+    return this.document.getElementById(id);
+  },
+
   toggle() {
     if (this._handler.isEnteringCustomizeMode || this._handler.isExitingCustomizeMode) {
       this._wantToBeInCustomizeMode = !this._wantToBeInCustomizeMode;
       return;
     }
     if (this._customizing) {
       this.exit();
     } else {
@@ -1572,80 +1581,70 @@ CustomizeMode.prototype = {
     delete this.paletteDragHandler;
   },
 
   observe(aSubject, aTopic, aData) {
     switch (aTopic) {
       case "nsPref:changed":
         this._updateResetButton();
         this._updateUndoResetButton();
-        if (AppConstants.CAN_DRAW_IN_TITLEBAR) {
+        if (this._canDrawInTitlebar()) {
           this._updateTitlebarCheckbox();
           this._updateDragSpaceCheckbox();
         }
         break;
     }
   },
 
+  _canDrawInTitlebar() {
+    return this.window.TabsInTitlebar.systemSupported;
+  },
+
   _updateTitlebarCheckbox() {
-    if (!AppConstants.CAN_DRAW_IN_TITLEBAR) {
-      return;
-    }
     let drawInTitlebar = Services.prefs.getBoolPref(kDrawInTitlebarPref, true);
-    let checkbox = this.document.getElementById("customization-titlebar-visibility-checkbox");
+    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
     // customize mode the button is hidden and properties don't work.
     if (drawInTitlebar) {
       checkbox.removeAttribute("checked");
     } else {
       checkbox.setAttribute("checked", "true");
     }
   },
 
   _updateDragSpaceCheckbox() {
-    if (!AppConstants.CAN_DRAW_IN_TITLEBAR) {
-      return;
-    }
-
     let extraDragSpace = Services.prefs.getBoolPref(kExtraDragSpacePref);
     let drawInTitlebar = Services.prefs.getBoolPref(kDrawInTitlebarPref, true);
-    let menuBar = this.document.getElementById("toolbar-menubar");
+    let menuBar = this.$("toolbar-menubar");
     let menuBarEnabled = menuBar
       && AppConstants.platform != "macosx"
       && menuBar.getAttribute("autohide") != "true";
 
-    let checkbox = this.document.getElementById("customization-extra-drag-space-checkbox");
+    let checkbox = this.$("customization-extra-drag-space-checkbox");
     if (extraDragSpace) {
       checkbox.setAttribute("checked", "true");
     } else {
       checkbox.removeAttribute("checked");
     }
 
     if (!drawInTitlebar || menuBarEnabled) {
       checkbox.setAttribute("disabled", "true");
     } else {
       checkbox.removeAttribute("disabled");
     }
   },
 
   toggleTitlebar(aShouldShowTitlebar) {
-    if (!AppConstants.CAN_DRAW_IN_TITLEBAR) {
-      return;
-    }
     // Drawing in the titlebar means not showing the titlebar, hence the negation:
     Services.prefs.setBoolPref(kDrawInTitlebarPref, !aShouldShowTitlebar);
     this._updateDragSpaceCheckbox();
   },
 
   toggleDragSpace(aShouldShowDragSpace) {
-    if (!AppConstants.CAN_DRAW_IN_TITLEBAR) {
-      return;
-    }
-
     Services.prefs.setBoolPref(kExtraDragSpacePref, aShouldShowDragSpace);
   },
 
   get _dwu() {
     if (!this.__dwu) {
       this.__dwu = this.window.QueryInterface(Ci.nsIInterfaceRequestor).getInterface(Ci.nsIDOMWindowUtils);
     }
     return this.__dwu;

--- a/browser/components/customizableui/content/customizeMode.inc.xul
+++ b/browser/components/customizableui/content/customizeMode.inc.xul
@@ -23,26 +23,24 @@
             <description id="customization-panelDescription">&customizeMode.overflowList.description;</description>
           </vbox>
           <box class="panel-inner-arrowcontentfooter" hidden="true"/>
         </box>
       </vbox>
     </vbox>
   </box>
   <hbox id="customization-footer">
-#ifdef CAN_DRAW_IN_TITLEBAR
     <checkbox id="customization-titlebar-visibility-checkbox" class="customizationmode-checkbox"
               label="&customizeMode.titlebar;"
 #NB: because oncommand fires after click, by the time we've fired, the checkbox binding
 #    will already have switched the button's state, so this is correct:
               oncommand="gCustomizeMode.toggleTitlebar(this.checked)"/>
     <checkbox id="customization-extra-drag-space-checkbox" class="customizationmode-checkbox"
               label="&customizeMode.extraDragSpace;"
               oncommand="gCustomizeMode.toggleDragSpace(this.checked)"/>
-#endif
     <button id="customization-toolbar-visibility-button" label="&customizeMode.toolbars2;" class="customizationmode-button" type="menu">
       <menupopup id="customization-toolbar-menu" onpopupshowing="onViewToolbarsPopupShowing(event)"/>
     </button>
     <button id="customization-lwtheme-button" label="&customizeMode.lwthemes;" class="customizationmode-button" type="menu">
       <panel type="arrow" id="customization-lwtheme-menu"
              onpopupshowing="gCustomizeMode.onLWThemesMenuShowing(event);"
              position="topcenter bottomleft"
              flip="none"

--- a/browser/components/customizableui/moz.build
+++ b/browser/components/customizableui/moz.build
@@ -15,13 +15,10 @@ EXTRA_JS_MODULES += [
     'CustomizableWidgets.jsm',
     'CustomizeMode.jsm',
     'DragPositionManager.jsm',
     'PanelMultiView.jsm',
     'ScrollbarSampler.jsm',
     'SearchWidgetTracker.jsm',
 ]
 
-if CONFIG['MOZ_WIDGET_TOOLKIT'] in ('windows', 'cocoa'):
-    DEFINES['CAN_DRAW_IN_TITLEBAR'] = 1
-
 with Files('**'):
     BUG_COMPONENT = ('Firefox', 'Toolbars and Customization')

--- a/browser/themes/osx/moz.build
+++ b/browser/themes/osx/moz.build
@@ -3,10 +3,8 @@
 # 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/.
 
 DIRS += ['communicator']
 
 JAR_MANIFESTS += ['jar.mn']
 
-DEFINES['CAN_DRAW_IN_TITLEBAR'] = 1
-

--- a/browser/themes/shared/tabs.inc.css
+++ b/browser/themes/shared/tabs.inc.css
@@ -647,23 +647,21 @@
  * Note that this doesn't perfectly solve the issue (dragged tabs
  * may still resize very slightly) on some DPI settings with uneven
  * scaling factors on Windows, because of bug 477157.
  */
 .tabbrowser-tab::before {
   margin-inline-start: -1px;
 }
 
-%ifdef CAN_DRAW_IN_TITLEBAR
 %ifdef MENUBAR_CAN_AUTOHIDE
 :root[tabsintitlebar]:not([extradragspace]) #toolbar-menubar[autohide=true] + #TabsToolbar > #tabbrowser-tabs > .tabbrowser-tab::after,
 %else
 :root[tabsintitlebar]:not([extradragspace]) .tabbrowser-tab::after,
 %endif
-%endif
 /* Show full height tab separators on hover. */
 .tabbrowser-tab:hover::after,
 #tabbrowser-tabs:not([movingtab]) > .tabbrowser-tab[beforehovered]::after {
   margin-top: var(--tabs-top-border-width);
   margin-bottom: 0;
 }
 
 /* Show full height tab separators on selected tabs. */

--- a/browser/themes/windows/moz.build
+++ b/browser/themes/windows/moz.build
@@ -3,11 +3,10 @@
 # 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/.
 
 DIRS += ['communicator']
 
 JAR_MANIFESTS += ['jar.mn']
 
-DEFINES['CAN_DRAW_IN_TITLEBAR'] = 1
 DEFINES['MENUBAR_CAN_AUTOHIDE'] = 1
 

--- a/toolkit/modules/AppConstants.jsm
+++ b/toolkit/modules/AppConstants.jsm
@@ -245,23 +245,16 @@ this.AppConstants = Object.freeze({
 
   MENUBAR_CAN_AUTOHIDE:
 #ifdef MENUBAR_CAN_AUTOHIDE
   true,
 #else
   false,
 #endif
 
-  CAN_DRAW_IN_TITLEBAR:
-#ifdef CAN_DRAW_IN_TITLEBAR
-  true,
-#else
-  false,
-#endif
-
   MOZ_ANDROID_HISTORY:
 #ifdef MOZ_ANDROID_HISTORY
   true,
 #else
   false,
 #endif
 
   MOZ_TOOLKIT_SEARCH:

--- a/toolkit/modules/moz.build
+++ b/toolkit/modules/moz.build
@@ -255,19 +255,16 @@ if CONFIG['MOZ_WIDGET_TOOLKIT'] == 'coco
 
 EXTRA_JS_MODULES.third_party.jsesc += ['third_party/jsesc/jsesc.js']
 EXTRA_JS_MODULES.sessionstore += [
     'sessionstore/PrivacyLevel.jsm',
     'sessionstore/SessionHistory.jsm',
     'sessionstore/Utils.jsm',
 ]
 
-if CONFIG['MOZ_WIDGET_TOOLKIT'] in ('windows', 'cocoa', 'gtk3'):
-    DEFINES['CAN_DRAW_IN_TITLEBAR'] = 1
-
 if CONFIG['MOZ_WIDGET_TOOLKIT'] in ('windows', 'gtk3'):
     DEFINES['MENUBAR_CAN_AUTOHIDE'] = 1
 
 if CONFIG['MOZ_WIDGET_TOOLKIT'] in ('windows', 'gtk3', 'cocoa'):
     DEFINES['HAVE_SHELL_SERVICE'] = 1
 
 EXTRA_PP_JS_MODULES += [
     'AppConstants.jsm',