--- a/browser/components/customizableui/content/jar.mn
+++ b/browser/components/customizableui/content/jar.mn
@@ -1,11 +1,11 @@
 # 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/.
 
 browser.jar:
   content/browser/customizableui/aboutCustomizing.xhtml
   content/browser/customizableui/panelUI.css
-  content/browser/customizableui/panelUI.js
+* content/browser/customizableui/panelUI.js
   content/browser/customizableui/panelUI.xml
   content/browser/customizableui/toolbar.xml
 

--- a/browser/components/customizableui/content/panelUI.inc.xul
+++ b/browser/components/customizableui/content/panelUI.inc.xul
@@ -17,29 +17,33 @@
       <footer id="PanelUI-footer">
         <toolbarbutton id="PanelUI-fxa-status" label="&fxaSignIn.label;"
                        oncommand="gFxAccounts.toggle(event);"
                        hidden="true"/>
 
         <hbox id="PanelUI-footer-inner">
           <toolbarbutton id="PanelUI-customize" label="&appMenuCustomize.label;"
                          exitLabel="&appMenuCustomizeExit.label;"
+                         tooltiptext="&appMenuCustomize.tooltip;"
+                         exitTooltiptext="&appMenuCustomizeExit.tooltip;"
                          oncommand="gCustomizeMode.toggle();"/>
           <toolbarseparator/>
           <toolbarbutton id="PanelUI-help" label="&helpMenu.label;"
-                         tooltiptext="&helpMenu.label;"
+                         tooltiptext="&appMenuHelp.tooltip;"
                          oncommand="PanelUI.showHelpView(this.parentNode);"/>
           <toolbarseparator/>
           <toolbarbutton id="PanelUI-quit"
 #ifdef XP_WIN
                          label="&quitApplicationCmdWin.label;"
-                         tooltiptext="&quitApplicationCmdWin.label;"
+#else
+#ifdef XP_MACOSX
+                         label="&quitApplicationCmdMac.label;"
 #else
                          label="&quitApplicationCmd.label;"
-                         tooltiptext="&quitApplicationCmd.label;"
+#endif
 #endif
                          command="cmd_quitApplication"/>
         </hbox>
       </footer>
     </panelview>
 
     <panelview id="PanelUI-history" flex="1">
       <label value="&appMenuHistory.label;" class="panel-subview-header"/>

--- a/browser/components/customizableui/content/panelUI.js
+++ b/browser/components/customizableui/content/panelUI.js
@@ -3,16 +3,18 @@
  * You can obtain one at http://mozilla.org/MPL/2.0/. */
 
 XPCOMUtils.defineLazyModuleGetter(this, "CustomizableUI",
                                   "resource:///modules/CustomizableUI.jsm");
 XPCOMUtils.defineLazyModuleGetter(this, "ScrollbarSampler",
                                   "resource:///modules/ScrollbarSampler.jsm");
 XPCOMUtils.defineLazyModuleGetter(this, "Promise",
                                   "resource://gre/modules/Promise.jsm");
+XPCOMUtils.defineLazyModuleGetter(this, "ShortcutUtils",
+                                  "resource://gre/modules/ShortcutUtils.jsm");
 /**
  * Maintains the state and dispatches events for the main menu panel.
  */
 
 const PanelUI = {
   /** Panel events that we listen for. **/
   get kEvents() ["popupshowing", "popupshown", "popuphiding", "popuphidden"],
   /**
@@ -231,16 +233,17 @@ const PanelUI = {
       } else {
         this.beginBatchUpdate();
         try {
           CustomizableUI.registerMenuPanel(this.contents);
         } finally {
           this.endBatchUpdate();
         }
       }
+      this._updateQuitTooltip();
       this.panel.hidden = false;
     }.bind(this)).then(null, Cu.reportError);
 
     return this._readyPromise;
   },
 
   /**
    * Switch the panel to the main view if it's not already
@@ -417,17 +420,36 @@ const PanelUI = {
     }
     items.appendChild(fragment);
 
     this.addEventListener("command", PanelUI);
   },
 
   _onHelpViewHide: function(aEvent) {
     this.removeEventListener("command", PanelUI);
-  }
+  },
+
+  _updateQuitTooltip: function() {
+#ifndef XP_WIN
+#ifdef XP_MACOSX
+    let tooltipId = "quit-button.tooltiptext.mac";
+    let brands = Services.strings.createBundle("chrome://branding/locale/brand.properties");
+    let stringArgs = [brands.GetStringFromName("brandShortName")];
+#else
+    let tooltipId = "quit-button.tooltiptext.linux";
+    let stringArgs = [];
+#endif
+
+    let key = document.getElementById("key_quitApplication");
+    stringArgs.push(ShortcutUtils.prettifyShortcut(key));
+    let tooltipString = CustomizableUI.getLocalizedProperty({x: tooltipId}, "x", stringArgs);
+    let quitButton = document.getElementById("PanelUI-quit");
+    quitButton.setAttribute("tooltiptext", tooltipString);
+#endif
+  },
 };
 
 /**
  * Gets the currently selected locale for display.
  * @return  the selected locale or "en-US" if none is selected
  */
 function getLocale() {
   try {

--- a/browser/components/customizableui/src/CustomizeMode.jsm
+++ b/browser/components/customizableui/src/CustomizeMode.jsm
@@ -169,16 +169,18 @@ CustomizeMode.prototype = {
       // while customizing.
       let mainView = window.PanelUI.mainView;
       let panelHolder = document.getElementById("customization-panelHolder");
       panelHolder.appendChild(mainView);
 
       let customizeButton = document.getElementById("PanelUI-customize");
       customizeButton.setAttribute("enterLabel", customizeButton.getAttribute("label"));
       customizeButton.setAttribute("label", customizeButton.getAttribute("exitLabel"));
+      customizeButton.setAttribute("enterTooltiptext", customizeButton.getAttribute("tooltiptext"));
+      customizeButton.setAttribute("tooltiptext", customizeButton.getAttribute("exitTooltiptext"));
 
       this._transitioning = true;
 
       let customizer = document.getElementById("customization-container");
       customizer.parentNode.selectedPanel = customizer;
       customizer.hidden = false;
 
       yield this._doTransition(true);
@@ -320,16 +322,18 @@ CustomizeMode.prototype = {
       this.dispatchToolboxEvent("customizationending");
 
       window.PanelUI.setMainView(window.PanelUI.mainView);
       window.PanelUI.menuButton.disabled = false;
 
       let customizeButton = document.getElementById("PanelUI-customize");
       customizeButton.setAttribute("exitLabel", customizeButton.getAttribute("label"));
       customizeButton.setAttribute("label", customizeButton.getAttribute("enterLabel"));
+      customizeButton.setAttribute("exitTooltiptext", customizeButton.getAttribute("tooltiptext"));
+      customizeButton.setAttribute("tooltiptext", customizeButton.getAttribute("enterTooltiptext"));
 
       // We have to use setAttribute/removeAttribute here instead of the
       // property because the XBL property will be set later, and right
       // now we'd be setting an expando, which breaks the XBL property.
       document.getElementById("PanelUI-help").removeAttribute("disabled");
       document.getElementById("PanelUI-quit").removeAttribute("disabled");
 
       // We need to set this._customizing to false before removing the tab

--- a/browser/locales/en-US/chrome/browser/browser.dtd
+++ b/browser/locales/en-US/chrome/browser/browser.dtd
@@ -331,22 +331,25 @@ These should match what Safari and other
 <!-- LOCALIZATION NOTE (historyUndoWindowMenu): see bug 394759 -->
 <!ENTITY historyUndoWindowMenu.label "Recently Closed Windows">
 <!ENTITY historyRestoreLastSession.label "Restore Previous Session">
 
 <!ENTITY showAllHistoryCmd2.label "Show All History">
 <!ENTITY showAllHistoryCmd.commandkey "H">
 
 <!ENTITY appMenuCustomize.label "Customize">
+<!ENTITY appMenuCustomize.tooltip "Customize the Menu and Toolbars">
 <!ENTITY appMenuCustomizeExit.label "Exit Customize">
+<!ENTITY appMenuCustomizeExit.tooltip "Finish Customizing">
 <!ENTITY appMenuHistory.label "History">
 <!ENTITY appMenuHistory.showAll.label "Show All History">
 <!ENTITY appMenuHistory.clearRecent.label "Clear Recent History…">
 <!ENTITY appMenuHistory.restoreSession.label "Restore Previous Session">
 <!ENTITY appMenuHistory.viewSidebar.label "View History Sidebar">
+<!ENTITY appMenuHelp.tooltip "Open Help Menu">
 
 <!ENTITY customizeMenu.addToToolbar.label "Add to Toolbar">
 <!ENTITY customizeMenu.addToToolbar.accesskey "A">
 <!ENTITY customizeMenu.addToPanel.label "Add to Menu">
 <!ENTITY customizeMenu.addToPanel.accesskey "M">
 <!ENTITY customizeMenu.moveToToolbar.label "Move to Toolbar">
 <!ENTITY customizeMenu.moveToToolbar.accesskey "o">
 <!-- LOCALIZATION NOTE (customizeMenu.moveToPanel.accesskey) can appear on the

--- a/browser/locales/en-US/chrome/browser/customizableui/customizableWidgets.properties
+++ b/browser/locales/en-US/chrome/browser/customizableui/customizableWidgets.properties
@@ -76,8 +76,14 @@ paste-button.tooltiptext = Paste
 feed-button.label = Subscribe
 feed-button.tooltiptext = Subscribe to this page…
 
 characterencoding-button.label = Character Encoding
 characterencoding-button.tooltiptext = Character encoding
 
 email-link-button.label = Email Link
 email-link-button.tooltiptext = Email Link
+
+# LOCALIZATION NOTE(quit-button.tooltiptext.linux): %S is the keyboard shortcut
+quit-button.tooltiptext.linux = Quit (%S)
+# LOCALIZATION NOTE(quit-button.tooltiptext.mac): %1$S is the brand name (e.g. Firefox),
+# %2$S is the keyboard shortcut
+quit-button.tooltiptext.mac = Quit %1$S (%2$S)