The Tor Browser: browser/components/customizableui/src/CustomizableUI.jsm@8bccb770b82d (annotated)

browser/components/customizableui/src/CustomizableUI.jsm@8bccb770b82d (annotated)

browser/components/customizableui/src/CustomizableUI.jsm

Wed, 31 Dec 2014 13:27:57 +0100

author: Michael Schloh von Bennewitz <michael@schloh.com>
date: Wed, 31 Dec 2014 13:27:57 +0100
branch: TOR_BUG_3246
changeset 6: 8bccb770b82d
permissions: -rw-r--r--

Ignore runtime configuration files generated during quality assurance.

 /* 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/. */
 "use strict";
 this.EXPORTED_SYMBOLS = ["CustomizableUI"];
 const {classes: Cc, interfaces: Ci, utils: Cu, results: Cr} = Components;
 Cu.import("resource://gre/modules/Services.jsm");
 Cu.import("resource://gre/modules/XPCOMUtils.jsm");
 XPCOMUtils.defineLazyModuleGetter(this, "PanelWideWidgetTracker",
   "resource:///modules/PanelWideWidgetTracker.jsm");
 XPCOMUtils.defineLazyModuleGetter(this, "CustomizableWidgets",
   "resource:///modules/CustomizableWidgets.jsm");
 XPCOMUtils.defineLazyModuleGetter(this, "DeferredTask",
   "resource://gre/modules/DeferredTask.jsm");
 XPCOMUtils.defineLazyModuleGetter(this, "PrivateBrowsingUtils",
   "resource://gre/modules/PrivateBrowsingUtils.jsm");
 XPCOMUtils.defineLazyModuleGetter(this, "Promise",
   "resource://gre/modules/Promise.jsm");
 XPCOMUtils.defineLazyGetter(this, "gWidgetsBundle", function() {
   const kUrl = "chrome://browser/locale/customizableui/customizableWidgets.properties";
   return Services.strings.createBundle(kUrl);
 });
 XPCOMUtils.defineLazyModuleGetter(this, "ShortcutUtils",
   "resource://gre/modules/ShortcutUtils.jsm");
 XPCOMUtils.defineLazyServiceGetter(this, "gELS",
   "@mozilla.org/eventlistenerservice;1", "nsIEventListenerService");
 const kNSXUL = "http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul";
 const kSpecialWidgetPfx = "customizableui-special-";
 const kPrefCustomizationState        = "browser.uiCustomization.state";
 const kPrefCustomizationAutoAdd      = "browser.uiCustomization.autoAdd";
 const kPrefCustomizationDebug        = "browser.uiCustomization.debug";
 const kPrefDrawInTitlebar            = "browser.tabs.drawInTitlebar";
 /**
  * The keys are the handlers that are fired when the event type (the value)
  * is fired on the subview. A widget that provides a subview has the option
  * of providing onViewShowing and onViewHiding event handlers.
  */
 const kSubviewEvents = [
   "ViewShowing",
   "ViewHiding"
 ];
 /**
  * gPalette is a map of every widget that CustomizableUI.jsm knows about, keyed
  * on their IDs.
  */
 let gPalette = new Map();
 /**
  * gAreas maps area IDs to Sets of properties about those areas. An area is a
  * place where a widget can be put.
  */
 let gAreas = new Map();
 /**
  * gPlacements maps area IDs to Arrays of widget IDs, indicating that the widgets
  * are placed within that area (either directly in the area node, or in the
  * customizationTarget of the node).
  */
 let gPlacements = new Map();
 /**
  * gFuturePlacements represent placements that will happen for areas that have
  * not yet loaded (due to lazy-loading). This can occur when add-ons register
  * widgets.
  */
 let gFuturePlacements = new Map();
 //XXXunf Temporary. Need a nice way to abstract functions to build widgets
 //       of these types.
 let gSupportedWidgetTypes = new Set(["button", "view", "custom"]);
 /**
  * gPanelsForWindow is a list of known panels in a window which we may need to close
  * should command events fire which target them.
  */
 let gPanelsForWindow = new WeakMap();
 /**
  * gSeenWidgets remembers which widgets the user has seen for the first time
  * before. This way, if a new widget is created, and the user has not seen it
  * before, it can be put in its default location. Otherwise, it remains in the
  * palette.
  */
 let gSeenWidgets = new Set();
 /**
  * gDirtyAreaCache is a set of area IDs for areas where items have been added,
  * moved or removed at least once. This set is persisted, and is used to
  * optimize building of toolbars in the default case where no toolbars should
  * be "dirty".
  */
 let gDirtyAreaCache = new Set();
 /**
  * gPendingBuildAreas is a map from area IDs to map from build nodes to their
  * existing children at the time of node registration, that are waiting
  * for the area to be registered
  */
 let gPendingBuildAreas = new Map();
 let gSavedState = null;
 let gRestoring = false;
 let gDirty = false;
 let gInBatchStack = 0;
 let gResetting = false;
 let gUndoResetting = false;
 /**
  * gBuildAreas maps area IDs to actual area nodes within browser windows.
  */
 let gBuildAreas = new Map();
 /**
  * gBuildWindows is a map of windows that have registered build areas, mapped
  * to a Set of known toolboxes in that window.
  */
 let gBuildWindows = new Map();
 let gNewElementCount = 0;
 let gGroupWrapperCache = new Map();
 let gSingleWrapperCache = new WeakMap();
 let gListeners = new Set();
 let gUIStateBeforeReset = {
   uiCustomizationState: null,
   drawInTitlebar: null,
 };
 let gModuleName = "[CustomizableUI]";
 #include logging.js
 let CustomizableUIInternal = {
   initialize: function() {
     LOG("Initializing");
     this.addListener(this);
     this._defineBuiltInWidgets();
     this.loadSavedState();
     let panelPlacements = [
       "edit-controls",
       "zoom-controls",
       "new-window-button",
       "privatebrowsing-button",
       "save-page-button",
       "print-button",
       "history-panelmenu",
       "fullscreen-button",
       "find-button",
       "preferences-button",
       "add-ons-button",
       "developer-button",
     ];
     if (gPalette.has("switch-to-metro-button")) {
       panelPlacements.push("switch-to-metro-button");
     }
 #ifdef NIGHTLY_BUILD
     if (gPalette.has("e10s-button")) {
       let newWindowIndex = panelPlacements.indexOf("new-window-button");
       if (newWindowIndex > -1) {
         panelPlacements.splice(newWindowIndex + 1, 0, "e10s-button");
       }
     }
 #endif
     let showCharacterEncoding = Services.prefs.getComplexValue(
       "browser.menu.showCharacterEncoding",
       Ci.nsIPrefLocalizedString
     ).data;
     if (showCharacterEncoding == "true") {
       panelPlacements.push("characterencoding-button");
     }
     this.registerArea(CustomizableUI.AREA_PANEL, {
       anchor: "PanelUI-menu-button",
       type: CustomizableUI.TYPE_MENU_PANEL,
       defaultPlacements: panelPlacements
     }, true);
     PanelWideWidgetTracker.init();
     this.registerArea(CustomizableUI.AREA_NAVBAR, {
       legacy: true,
       type: CustomizableUI.TYPE_TOOLBAR,
       overflowable: true,
       defaultPlacements: [
         "urlbar-container",
         "search-container",
         "webrtc-status-button",
         "bookmarks-menu-button",
         "downloads-button",
         "home-button",
         "social-share-button",
       ],
       defaultCollapsed: false,
     }, true);
 #ifndef XP_MACOSX
     this.registerArea(CustomizableUI.AREA_MENUBAR, {
       legacy: true,
       type: CustomizableUI.TYPE_TOOLBAR,
       defaultPlacements: [
         "menubar-items",
       ],
       get defaultCollapsed() {
 #ifdef MENUBAR_CAN_AUTOHIDE
 #if defined(MOZ_WIDGET_GTK) || defined(MOZ_WIDGET_QT)
         return true;
 #else
         // This is duplicated logic from /browser/base/jar.mn
         // for win6BrowserOverlay.xul.
         return Services.appinfo.OS == "WINNT" &&
                Services.sysinfo.getProperty("version") != "5.1";
 #endif
 #endif
         return false;
       }
     }, true);
 #endif
     this.registerArea(CustomizableUI.AREA_TABSTRIP, {
       legacy: true,
       type: CustomizableUI.TYPE_TOOLBAR,
       defaultPlacements: [
         "tabbrowser-tabs",
         "new-tab-button",
         "alltabs-button",
       ],
       defaultCollapsed: null,
     }, true);
     this.registerArea(CustomizableUI.AREA_BOOKMARKS, {
       legacy: true,
       type: CustomizableUI.TYPE_TOOLBAR,
       defaultPlacements: [
         "personal-bookmarks",
       ],
       defaultCollapsed: true,
     }, true);
     this.registerArea(CustomizableUI.AREA_ADDONBAR, {
       type: CustomizableUI.TYPE_TOOLBAR,
       legacy: true,
       defaultPlacements: ["addonbar-closebutton", "status-bar"],
       defaultCollapsed: false,
     }, true);
   },
   get _builtinToolbars() {
     return new Set([
       CustomizableUI.AREA_NAVBAR,
       CustomizableUI.AREA_BOOKMARKS,
       CustomizableUI.AREA_TABSTRIP,
       CustomizableUI.AREA_ADDONBAR,
 #ifndef XP_MACOSX
       CustomizableUI.AREA_MENUBAR,
 #endif
     ]);
   },
   _defineBuiltInWidgets: function() {
     //XXXunf Need to figure out how to auto-add new builtin widgets in new
     //       app versions to already customized areas.
     for (let widgetDefinition of CustomizableWidgets) {
       this.createBuiltinWidget(widgetDefinition);
     }
   },
   wrapWidget: function(aWidgetId) {
     if (gGroupWrapperCache.has(aWidgetId)) {
       return gGroupWrapperCache.get(aWidgetId);
     }
     let provider = this.getWidgetProvider(aWidgetId);
     if (!provider) {
       return null;
     }
     if (provider == CustomizableUI.PROVIDER_API) {
       let widget = gPalette.get(aWidgetId);
       if (!widget.wrapper) {
         widget.wrapper = new WidgetGroupWrapper(widget);
         gGroupWrapperCache.set(aWidgetId, widget.wrapper);
       }
       return widget.wrapper;
     }
     // PROVIDER_SPECIAL gets treated the same as PROVIDER_XUL.
     let wrapper = new XULWidgetGroupWrapper(aWidgetId);
     gGroupWrapperCache.set(aWidgetId, wrapper);
     return wrapper;
   },
   registerArea: function(aName, aProperties, aInternalCaller) {
     if (typeof aName != "string" || !/^[a-z0-9-_]{1,}$/i.test(aName)) {
       throw new Error("Invalid area name");
     }
     let areaIsKnown = gAreas.has(aName);
     let props = areaIsKnown ? gAreas.get(aName) : new Map();
     const kImmutableProperties = new Set(["type", "legacy", "overflowable"]);
     for (let key in aProperties) {
       if (areaIsKnown && kImmutableProperties.has(key) &&
           props.get(key) != aProperties[key]) {
         throw new Error("An area cannot change the property for '" + key + "'");
       }
       //XXXgijs for special items, we need to make sure they have an appropriate ID
       // so we aren't perpetually in a non-default state:
       if (key == "defaultPlacements" && Array.isArray(aProperties[key])) {
         props.set(key, aProperties[key].map(x => this.isSpecialWidget(x) ? this.ensureSpecialWidgetId(x) : x ));
       } else {
         props.set(key, aProperties[key]);
       }
     }
     // Default to a toolbar:
     if (!props.has("type")) {
       props.set("type", CustomizableUI.TYPE_TOOLBAR);
     }
     if (props.get("type") == CustomizableUI.TYPE_TOOLBAR) {
       // Check aProperties instead of props because this check is only interested
       // in the passed arguments, not the state of a potentially pre-existing area.
       if (!aInternalCaller && aProperties["defaultCollapsed"]) {
         throw new Error("defaultCollapsed is only allowed for default toolbars.")
       }
       if (!props.has("defaultCollapsed")) {
         props.set("defaultCollapsed", true);
       }
     } else if (props.has("defaultCollapsed")) {
       throw new Error("defaultCollapsed only applies for TYPE_TOOLBAR areas.");
     }
     // Sanity check type:
     let allTypes = [CustomizableUI.TYPE_TOOLBAR, CustomizableUI.TYPE_MENU_PANEL];
     if (allTypes.indexOf(props.get("type")) == -1) {
       throw new Error("Invalid area type " + props.get("type"));
     }
     // And to no placements:
     if (!props.has("defaultPlacements")) {
       props.set("defaultPlacements", []);
     }
     // Sanity check default placements array:
     if (!Array.isArray(props.get("defaultPlacements"))) {
       throw new Error("Should provide an array of default placements");
     }
     if (!areaIsKnown) {
       gAreas.set(aName, props);
       if (props.get("legacy") && !gPlacements.has(aName)) {
         // Guarantee this area exists in gFuturePlacements, to avoid checking it in
         // various places elsewhere.
         gFuturePlacements.set(aName, new Set());
       } else {
         this.restoreStateForArea(aName);
       }
       // If we have pending build area nodes, register all of them
       if (gPendingBuildAreas.has(aName)) {
         let pendingNodes = gPendingBuildAreas.get(aName);
         for (let [pendingNode, existingChildren] of pendingNodes) {
           this.registerToolbarNode(pendingNode, existingChildren);
         }
         gPendingBuildAreas.delete(aName);
       }
     }
   },
   unregisterArea: function(aName, aDestroyPlacements) {
     if (typeof aName != "string" || !/^[a-z0-9-_]{1,}$/i.test(aName)) {
       throw new Error("Invalid area name");
     }
     if (!gAreas.has(aName) && !gPlacements.has(aName)) {
       throw new Error("Area not registered");
     }
     // Move all the widgets out
     this.beginBatchUpdate();
     try {
       let placements = gPlacements.get(aName);
       if (placements) {
         // Need to clone this array so removeWidgetFromArea doesn't modify it
         placements = [...placements];
         placements.forEach(this.removeWidgetFromArea, this);
       }
       // Delete all remaining traces.
       gAreas.delete(aName);
       // Only destroy placements when necessary:
       if (aDestroyPlacements) {
         gPlacements.delete(aName);
       } else {
         // Otherwise we need to re-set them, as removeFromArea will have emptied
         // them out:
         gPlacements.set(aName, placements);
       }
       gFuturePlacements.delete(aName);
       let existingAreaNodes = gBuildAreas.get(aName);
       if (existingAreaNodes) {
         for (let areaNode of existingAreaNodes) {
           this.notifyListeners("onAreaNodeUnregistered", aName, areaNode.customizationTarget,
                                CustomizableUI.REASON_AREA_UNREGISTERED);
         }
       }
       gBuildAreas.delete(aName);
     } finally {
       this.endBatchUpdate(true);
     }
   },
   registerToolbarNode: function(aToolbar, aExistingChildren) {
     let area = aToolbar.id;
     if (gBuildAreas.has(area) && gBuildAreas.get(area).has(aToolbar)) {
       return;
     }
     let document = aToolbar.ownerDocument;
     let areaProperties = gAreas.get(area);
     // If this area is not registered, try to do it automatically:
     if (!areaProperties) {
       // If there's no defaultset attribute and this isn't a legacy extra toolbar,
       // we assume that we should wait for registerArea to be called:
       if (!aToolbar.hasAttribute("defaultset") &&
           !aToolbar.hasAttribute("customindex")) {
         if (!gPendingBuildAreas.has(area)) {
           gPendingBuildAreas.set(area, new Map());
         }
         let pendingNodes = gPendingBuildAreas.get(area);
         pendingNodes.set(aToolbar, aExistingChildren);
         return;
       }
       let props = {type: CustomizableUI.TYPE_TOOLBAR, legacy: true};
       let defaultsetAttribute = aToolbar.getAttribute("defaultset") || "";
       props.defaultPlacements = defaultsetAttribute.split(',').filter(s => s);
       this.registerArea(area, props);
       areaProperties = gAreas.get(area);
     }
     this.beginBatchUpdate();
     try {
       let placements = gPlacements.get(area);
       if (!placements && areaProperties.has("legacy")) {
         let legacyState = aToolbar.getAttribute("currentset");
         if (legacyState) {
           legacyState = legacyState.split(",").filter(s => s);
         }
         // Manually restore the state here, so the legacy state can be converted.
         this.restoreStateForArea(area, legacyState);
         placements = gPlacements.get(area);
       }
       // Check that the current children and the current placements match. If
       // not, mark it as dirty:
       if (aExistingChildren.length != placements.length ||
           aExistingChildren.every((id, i) => id == placements[i])) {
         gDirtyAreaCache.add(area);
       }
       if (areaProperties.has("overflowable")) {
         aToolbar.overflowable = new OverflowableToolbar(aToolbar);
       }
       this.registerBuildArea(area, aToolbar);
       // We only build the toolbar if it's been marked as "dirty". Dirty means
       // one of the following things:
       // 1) Items have been added, moved or removed from this toolbar before.
       // 2) The number of children of the toolbar does not match the length of
       //    the placements array for that area.
       //
       // This notion of being "dirty" is stored in a cache which is persisted
       // in the saved state.
       if (gDirtyAreaCache.has(area)) {
         this.buildArea(area, placements, aToolbar);
       }
       this.notifyListeners("onAreaNodeRegistered", area, aToolbar.customizationTarget);
       aToolbar.setAttribute("currentset", placements.join(","));
     } finally {
       this.endBatchUpdate();
     }
   },
   buildArea: function(aArea, aPlacements, aAreaNode) {
     let document = aAreaNode.ownerDocument;
     let window = document.defaultView;
     let inPrivateWindow = PrivateBrowsingUtils.isWindowPrivate(window);
     let container = aAreaNode.customizationTarget;
     let areaIsPanel = gAreas.get(aArea).get("type") == CustomizableUI.TYPE_MENU_PANEL;
     if (!container) {
       throw new Error("Expected area " + aArea
                       + " to have a customizationTarget attribute.");
     }
     // Restore nav-bar visibility since it may have been hidden
     // through a migration path (bug 938980) or an add-on.
     if (aArea == CustomizableUI.AREA_NAVBAR) {
       aAreaNode.collapsed = false;
     }
     this.beginBatchUpdate();
     try {
       let currentNode = container.firstChild;
       let placementsToRemove = new Set();
       for (let id of aPlacements) {
         while (currentNode && currentNode.getAttribute("skipintoolbarset") == "true") {
           currentNode = currentNode.nextSibling;
         }
         if (currentNode && currentNode.id == id) {
           currentNode = currentNode.nextSibling;
           continue;
         }
         if (this.isSpecialWidget(id) && areaIsPanel) {
           placementsToRemove.add(id);
           continue;
         }
         let [provider, node] = this.getWidgetNode(id, window);
         if (!node) {
           LOG("Unknown widget: " + id);
           continue;
         }
         // If the placements have items in them which are (now) no longer removable,
         // we shouldn't be moving them:
         if (provider == CustomizableUI.PROVIDER_API) {
           let widgetInfo = gPalette.get(id);
           if (!widgetInfo.removable && aArea != widgetInfo.defaultArea) {
             placementsToRemove.add(id);
             continue;
           }
         } else if (provider == CustomizableUI.PROVIDER_XUL &&
                    node.parentNode != container && !this.isWidgetRemovable(node)) {
           placementsToRemove.add(id);
           continue;
         } // Special widgets are always removable, so no need to check them
         if (inPrivateWindow && provider == CustomizableUI.PROVIDER_API) {
           let widget = gPalette.get(id);
           if (!widget.showInPrivateBrowsing && inPrivateWindow) {
             continue;
           }
         }
         this.ensureButtonContextMenu(node, aAreaNode);
         if (node.localName == "toolbarbutton") {
           if (areaIsPanel) {
             node.setAttribute("wrap", "true");
           } else {
             node.removeAttribute("wrap");
           }
         }
         this.insertWidgetBefore(node, currentNode, container, aArea);
         if (gResetting) {
           this.notifyListeners("onWidgetReset", node, container);
         } else if (gUndoResetting) {
           this.notifyListeners("onWidgetUndoMove", node, container);
         }
       }
       if (currentNode) {
         let palette = aAreaNode.toolbox ? aAreaNode.toolbox.palette : null;
         let limit = currentNode.previousSibling;
         let node = container.lastChild;
         while (node && node != limit) {
           let previousSibling = node.previousSibling;
           // Nodes opt-in to removability. If they're removable, and we haven't
           // seen them in the placements array, then we toss them into the palette
           // if one exists. If no palette exists, we just remove the node. If the
           // node is not removable, we leave it where it is. However, we can only
           // safely touch elements that have an ID - both because we depend on
           // IDs, and because such elements are not intended to be widgets
           // (eg, titlebar-placeholder elements).
           if (node.id && node.getAttribute("skipintoolbarset") != "true") {
             if (this.isWidgetRemovable(node)) {
               if (palette && !this.isSpecialWidget(node.id)) {
                 palette.appendChild(node);
                 this.removeLocationAttributes(node);
               } else {
                 container.removeChild(node);
               }
             } else {
               this.setLocationAttributes(currentNode, aArea);
               node.setAttribute("removable", false);
               LOG("Adding non-removable widget to placements of " + aArea + ": " +
                   node.id);
               gPlacements.get(aArea).push(node.id);
               gDirty = true;
             }
           }
           node = previousSibling;
         }
       }
       // If there are placements in here which aren't removable from their original area,
       // we remove them from this area's placement array. They will (have) be(en) added
       // to their original area's placements array in the block above this one.
       if (placementsToRemove.size) {
         let placementAry = gPlacements.get(aArea);
         for (let id of placementsToRemove) {
           let index = placementAry.indexOf(id);
           placementAry.splice(index, 1);
         }
       }
       if (gResetting) {
         this.notifyListeners("onAreaReset", aArea, container);
       }
     } finally {
       this.endBatchUpdate();
     }
   },
   addPanelCloseListeners: function(aPanel) {
     gELS.addSystemEventListener(aPanel, "click", this, false);
     gELS.addSystemEventListener(aPanel, "keypress", this, false);
     let win = aPanel.ownerDocument.defaultView;
     if (!gPanelsForWindow.has(win)) {
       gPanelsForWindow.set(win, new Set());
     }
     gPanelsForWindow.get(win).add(this._getPanelForNode(aPanel));
   },
   removePanelCloseListeners: function(aPanel) {
     gELS.removeSystemEventListener(aPanel, "click", this, false);
     gELS.removeSystemEventListener(aPanel, "keypress", this, false);
     let win = aPanel.ownerDocument.defaultView;
     let panels = gPanelsForWindow.get(win);
     if (panels) {
       panels.delete(this._getPanelForNode(aPanel));
     }
   },
   ensureButtonContextMenu: function(aNode, aAreaNode) {
     const kPanelItemContextMenu = "customizationPanelItemContextMenu";
     let currentContextMenu = aNode.getAttribute("context") ||
                              aNode.getAttribute("contextmenu");
     let place = CustomizableUI.getPlaceForItem(aAreaNode);
     let contextMenuForPlace = place == "panel" ?
                                 kPanelItemContextMenu :
                                 null;
     if (contextMenuForPlace && !currentContextMenu) {
       aNode.setAttribute("context", contextMenuForPlace);
     } else if (currentContextMenu == kPanelItemContextMenu &&
                contextMenuForPlace != kPanelItemContextMenu) {
       aNode.removeAttribute("context");
       aNode.removeAttribute("contextmenu");
     }
   },
   getWidgetProvider: function(aWidgetId) {
     if (this.isSpecialWidget(aWidgetId)) {
       return CustomizableUI.PROVIDER_SPECIAL;
     }
     if (gPalette.has(aWidgetId)) {
       return CustomizableUI.PROVIDER_API;
     }
     // If this was an API widget that was destroyed, return null:
     if (gSeenWidgets.has(aWidgetId)) {
       return null;
     }
     // We fall back to the XUL provider, but we don't know for sure (at this
     // point) whether it exists there either. So the API is technically lying.
     // Ideally, it would be able to return an error value (or throw an
     // exception) if it really didn't exist. Our code calling this function
     // handles that fine, but this is a public API.
     return CustomizableUI.PROVIDER_XUL;
   },
   getWidgetNode: function(aWidgetId, aWindow) {
     let document = aWindow.document;
     if (this.isSpecialWidget(aWidgetId)) {
       let widgetNode = document.getElementById(aWidgetId) ||
                        this.createSpecialWidget(aWidgetId, document);
       return [ CustomizableUI.PROVIDER_SPECIAL, widgetNode];
     }
     let widget = gPalette.get(aWidgetId);
     if (widget) {
       // If we have an instance of this widget already, just use that.
       if (widget.instances.has(document)) {
         LOG("An instance of widget " + aWidgetId + " already exists in this "
             + "document. Reusing.");
         return [ CustomizableUI.PROVIDER_API,
                  widget.instances.get(document) ];
       }
       return [ CustomizableUI.PROVIDER_API,
                this.buildWidget(document, widget) ];
     }
     LOG("Searching for " + aWidgetId + " in toolbox.");
     let node = this.findWidgetInWindow(aWidgetId, aWindow);
     if (node) {
       return [ CustomizableUI.PROVIDER_XUL, node ];
     }
     LOG("No node for " + aWidgetId + " found.");
     return [null, null];
   },
   registerMenuPanel: function(aPanelContents) {
     if (gBuildAreas.has(CustomizableUI.AREA_PANEL) &&
         gBuildAreas.get(CustomizableUI.AREA_PANEL).has(aPanelContents)) {
       return;
     }
     let document = aPanelContents.ownerDocument;
     aPanelContents.toolbox = document.getElementById("navigator-toolbox");
     aPanelContents.customizationTarget = aPanelContents;
     this.addPanelCloseListeners(this._getPanelForNode(aPanelContents));
     let placements = gPlacements.get(CustomizableUI.AREA_PANEL);
     this.buildArea(CustomizableUI.AREA_PANEL, placements, aPanelContents);
     this.notifyListeners("onAreaNodeRegistered", CustomizableUI.AREA_PANEL, aPanelContents);
     for (let child of aPanelContents.children) {
       if (child.localName != "toolbarbutton") {
         if (child.localName == "toolbaritem") {
           this.ensureButtonContextMenu(child, aPanelContents);
         }
         continue;
       }
       this.ensureButtonContextMenu(child, aPanelContents);
       child.setAttribute("wrap", "true");
     }
     this.registerBuildArea(CustomizableUI.AREA_PANEL, aPanelContents);
   },
   onWidgetAdded: function(aWidgetId, aArea, aPosition) {
     this.insertNode(aWidgetId, aArea, aPosition, true);
     if (!gResetting) {
       this._clearPreviousUIState();
     }
   },
   onWidgetRemoved: function(aWidgetId, aArea) {
     let areaNodes = gBuildAreas.get(aArea);
     if (!areaNodes) {
       return;
     }
     let area = gAreas.get(aArea);
     let isToolbar = area.get("type") == CustomizableUI.TYPE_TOOLBAR;
     let isOverflowable = isToolbar && area.get("overflowable");
     let showInPrivateBrowsing = gPalette.has(aWidgetId)
                               ? gPalette.get(aWidgetId).showInPrivateBrowsing
                               : true;
     for (let areaNode of areaNodes) {
       let window = areaNode.ownerDocument.defaultView;
       if (!showInPrivateBrowsing &&
           PrivateBrowsingUtils.isWindowPrivate(window)) {
         continue;
       }
       let widgetNode = window.document.getElementById(aWidgetId);
       if (!widgetNode) {
         INFO("Widget not found, unable to remove");
         continue;
       }
       let container = areaNode.customizationTarget;
       if (isOverflowable) {
         container = areaNode.overflowable.getContainerFor(widgetNode);
       }
       this.notifyListeners("onWidgetBeforeDOMChange", widgetNode, null, container, true);
       // We remove location attributes here to make sure they're gone too when a
       // widget is removed from a toolbar to the palette. See bug 930950.
       this.removeLocationAttributes(widgetNode);
       // We also need to remove the panel context menu if it's there:
       this.ensureButtonContextMenu(widgetNode);
       widgetNode.removeAttribute("wrap");
       if (gPalette.has(aWidgetId) || this.isSpecialWidget(aWidgetId)) {
         container.removeChild(widgetNode);
       } else {
         areaNode.toolbox.palette.appendChild(widgetNode);
       }
       this.notifyListeners("onWidgetAfterDOMChange", widgetNode, null, container, true);
       if (isToolbar) {
         areaNode.setAttribute("currentset", gPlacements.get(aArea).join(','));
       }
       let windowCache = gSingleWrapperCache.get(window);
       if (windowCache) {
         windowCache.delete(aWidgetId);
       }
     }
     if (!gResetting) {
       this._clearPreviousUIState();
     }
   },
   onWidgetMoved: function(aWidgetId, aArea, aOldPosition, aNewPosition) {
     this.insertNode(aWidgetId, aArea, aNewPosition);
     if (!gResetting) {
       this._clearPreviousUIState();
     }
   },
   onCustomizeEnd: function(aWindow) {
     this._clearPreviousUIState();
   },
   registerBuildArea: function(aArea, aNode) {
     // We ensure that the window is registered to have its customization data
     // cleaned up when unloading.
     let window = aNode.ownerDocument.defaultView;
     if (window.closed) {
       return;
     }
     this.registerBuildWindow(window);
     // Also register this build area's toolbox.
     if (aNode.toolbox) {
       gBuildWindows.get(window).add(aNode.toolbox);
     }
     if (!gBuildAreas.has(aArea)) {
       gBuildAreas.set(aArea, new Set());
     }
     gBuildAreas.get(aArea).add(aNode);
     // Give a class to all customize targets to be used for styling in Customize Mode
     let customizableNode = this.getCustomizeTargetForArea(aArea, window);
     customizableNode.classList.add("customization-target");
   },
   registerBuildWindow: function(aWindow) {
     if (!gBuildWindows.has(aWindow)) {
       gBuildWindows.set(aWindow, new Set());
       aWindow.addEventListener("unload", this);
       aWindow.addEventListener("command", this, true);
       this.notifyListeners("onWindowOpened", aWindow);
     }
   },
   unregisterBuildWindow: function(aWindow) {
     aWindow.removeEventListener("unload", this);
     aWindow.removeEventListener("command", this, true);
     gPanelsForWindow.delete(aWindow);
     gBuildWindows.delete(aWindow);
     gSingleWrapperCache.delete(aWindow);
     let document = aWindow.document;
     for (let [areaId, areaNodes] of gBuildAreas) {
       let areaProperties = gAreas.get(areaId);
       for (let node of areaNodes) {
         if (node.ownerDocument == document) {
           this.notifyListeners("onAreaNodeUnregistered", areaId, node.customizationTarget,
                                CustomizableUI.REASON_WINDOW_CLOSED);
           if (areaProperties.has("overflowable")) {
             node.overflowable.uninit();
             node.overflowable = null;
           }
           areaNodes.delete(node);
         }
       }
     }
     for (let [,widget] of gPalette) {
       widget.instances.delete(document);
       this.notifyListeners("onWidgetInstanceRemoved", widget.id, document);
     }
     for (let [area, areaMap] of gPendingBuildAreas) {
       let toDelete = [];
       for (let [areaNode, ] of areaMap) {
         if (areaNode.ownerDocument == document) {
           toDelete.push(areaNode);
         }
       }
       for (let areaNode of toDelete) {
         areaMap.delete(toDelete);
       }
     }
     this.notifyListeners("onWindowClosed", aWindow);
   },
   setLocationAttributes: function(aNode, aArea) {
     let props = gAreas.get(aArea);
     if (!props) {
       throw new Error("Expected area " + aArea + " to have a properties Map " +
                       "associated with it.");
     }
     aNode.setAttribute("cui-areatype", props.get("type") || "");
     let anchor = props.get("anchor");
     if (anchor) {
       aNode.setAttribute("cui-anchorid", anchor);
     } else {
       aNode.removeAttribute("cui-anchorid");
     }
   },
   removeLocationAttributes: function(aNode) {
     aNode.removeAttribute("cui-areatype");
     aNode.removeAttribute("cui-anchorid");
   },
   insertNode: function(aWidgetId, aArea, aPosition, isNew) {
     let areaNodes = gBuildAreas.get(aArea);
     if (!areaNodes) {
       return;
     }
     let placements = gPlacements.get(aArea);
     if (!placements) {
       ERROR("Could not find any placements for " + aArea +
             " when moving a widget.");
       return;
     }
     // Go through each of the nodes associated with this area and move the
     // widget to the requested location.
     for (let areaNode of areaNodes) {
       this.insertNodeInWindow(aWidgetId, areaNode, isNew);
     }
   },
   insertNodeInWindow: function(aWidgetId, aAreaNode, isNew) {
     let window = aAreaNode.ownerDocument.defaultView;
     let showInPrivateBrowsing = gPalette.has(aWidgetId)
                               ? gPalette.get(aWidgetId).showInPrivateBrowsing
                               : true;
     if (!showInPrivateBrowsing && PrivateBrowsingUtils.isWindowPrivate(window)) {
       return;
     }
     let [, widgetNode] = this.getWidgetNode(aWidgetId, window);
     if (!widgetNode) {
       ERROR("Widget '" + aWidgetId + "' not found, unable to move");
       return;
     }
     let areaId = aAreaNode.id;
     if (isNew) {
       this.ensureButtonContextMenu(widgetNode, aAreaNode);
       if (widgetNode.localName == "toolbarbutton" && areaId == CustomizableUI.AREA_PANEL) {
         widgetNode.setAttribute("wrap", "true");
       }
     }
     let [insertionContainer, nextNode] = this.findInsertionPoints(widgetNode, aAreaNode);
     this.insertWidgetBefore(widgetNode, nextNode, insertionContainer, areaId);
     if (gAreas.get(areaId).get("type") == CustomizableUI.TYPE_TOOLBAR) {
       aAreaNode.setAttribute("currentset", gPlacements.get(areaId).join(','));
     }
   },
   findInsertionPoints: function(aNode, aAreaNode) {
     let areaId = aAreaNode.id;
     let props = gAreas.get(areaId);
     // For overflowable toolbars, rely on them (because the work is more complicated):
     if (props.get("type") == CustomizableUI.TYPE_TOOLBAR && props.get("overflowable")) {
       return aAreaNode.overflowable.findOverflowedInsertionPoints(aNode);
     }
     let container = aAreaNode.customizationTarget;
     let placements = gPlacements.get(areaId);
     let nodeIndex = placements.indexOf(aNode.id);
     while (++nodeIndex < placements.length) {
       let nextNodeId = placements[nodeIndex];
       let nextNode = container.getElementsByAttribute("id", nextNodeId).item(0);
       if (nextNode) {
         return [container, nextNode];
       }
     }
     return [container, null];
   },
   insertWidgetBefore: function(aNode, aNextNode, aContainer, aArea) {
     this.notifyListeners("onWidgetBeforeDOMChange", aNode, aNextNode, aContainer);
     this.setLocationAttributes(aNode, aArea);
     aContainer.insertBefore(aNode, aNextNode);
     this.notifyListeners("onWidgetAfterDOMChange", aNode, aNextNode, aContainer);
   },
   handleEvent: function(aEvent) {
     switch (aEvent.type) {
       case "command":
         if (!this._originalEventInPanel(aEvent)) {
           break;
         }
         aEvent = aEvent.sourceEvent;
         // Fall through
       case "click":
       case "keypress":
         this.maybeAutoHidePanel(aEvent);
         break;
       case "unload":
         this.unregisterBuildWindow(aEvent.currentTarget);
         break;
     }
   },
   _originalEventInPanel: function(aEvent) {
     let e = aEvent.sourceEvent;
     if (!e) {
       return false;
     }
     let node = this._getPanelForNode(e.target);
     if (!node) {
       return false;
     }
     let win = e.view;
     let panels = gPanelsForWindow.get(win);
     return !!panels && panels.has(node);
   },
   isSpecialWidget: function(aId) {
     return (aId.startsWith(kSpecialWidgetPfx) ||
             aId.startsWith("separator") ||
             aId.startsWith("spring") ||
             aId.startsWith("spacer"));
   },
   ensureSpecialWidgetId: function(aId) {
     let nodeType = aId.match(/spring|spacer|separator/)[0];
     // If the ID we were passed isn't a generated one, generate one now:
     if (nodeType == aId) {
       // Ids are differentiated through a unique count suffix.
       return kSpecialWidgetPfx + aId + (++gNewElementCount);
     }
     return aId;
   },
   createSpecialWidget: function(aId, aDocument) {
     let nodeName = "toolbar" + aId.match(/spring|spacer|separator/)[0];
     let node = aDocument.createElementNS(kNSXUL, nodeName);
     node.id = this.ensureSpecialWidgetId(aId);
     if (nodeName == "toolbarspring") {
       node.flex = 1;
     }
     return node;
   },
   /* Find a XUL-provided widget in a window. Don't try to use this
    * for an API-provided widget or a special widget.
    */
   findWidgetInWindow: function(aId, aWindow) {
     if (!gBuildWindows.has(aWindow)) {
       throw new Error("Build window not registered");
     }
     if (!aId) {
       ERROR("findWidgetInWindow was passed an empty string.");
       return null;
     }
     let document = aWindow.document;
     // look for a node with the same id, as the node may be
     // in a different toolbar.
     let node = document.getElementById(aId);
     if (node) {
       let parent = node.parentNode;
       while (parent && !(parent.customizationTarget ||
                          parent == aWindow.gNavToolbox.palette)) {
         parent = parent.parentNode;
       }
       if (parent) {
         let nodeInArea = node.parentNode.localName == "toolbarpaletteitem" ?
                          node.parentNode : node;
         // Check if we're in a customization target, or in the palette:
         if ((parent.customizationTarget == nodeInArea.parentNode &&
              gBuildWindows.get(aWindow).has(parent.toolbox)) ||
             aWindow.gNavToolbox.palette == nodeInArea.parentNode) {
           // Normalize the removable attribute. For backwards compat, if
           // the widget is not located in a toolbox palette then absence
           // of the "removable" attribute means it is not removable.
           if (!node.hasAttribute("removable")) {
             // If we first see this in customization mode, it may be in the
             // customization palette instead of the toolbox palette.
             node.setAttribute("removable", !parent.customizationTarget);
           }
           return node;
         }
       }
     }
     let toolboxes = gBuildWindows.get(aWindow);
     for (let toolbox of toolboxes) {
       if (toolbox.palette) {
         // Attempt to locate a node with a matching ID within
         // the palette.
         let node = toolbox.palette.getElementsByAttribute("id", aId)[0];
         if (node) {
           // Normalize the removable attribute. For backwards compat, this
           // is optional if the widget is located in the toolbox palette,
           // and defaults to *true*, unlike if it was located elsewhere.
           if (!node.hasAttribute("removable")) {
             node.setAttribute("removable", true);
           }
           return node;
         }
       }
     }
     return null;
   },
   buildWidget: function(aDocument, aWidget) {
     if (typeof aWidget == "string") {
       aWidget = gPalette.get(aWidget);
     }
     if (!aWidget) {
       throw new Error("buildWidget was passed a non-widget to build.");
     }
     LOG("Building " + aWidget.id + " of type " + aWidget.type);
     let node;
     if (aWidget.type == "custom") {
       if (aWidget.onBuild) {
         node = aWidget.onBuild(aDocument);
       }
       if (!node || !(node instanceof aDocument.defaultView.XULElement))
         ERROR("Custom widget with id " + aWidget.id + " does not return a valid node");
     }
     else {
       if (aWidget.onBeforeCreated) {
         aWidget.onBeforeCreated(aDocument);
       }
       node = aDocument.createElementNS(kNSXUL, "toolbarbutton");
       node.setAttribute("id", aWidget.id);
       node.setAttribute("widget-id", aWidget.id);
       node.setAttribute("widget-type", aWidget.type);
       if (aWidget.disabled) {
         node.setAttribute("disabled", true);
       }
       node.setAttribute("removable", aWidget.removable);
       node.setAttribute("overflows", aWidget.overflows);
       node.setAttribute("label", this.getLocalizedProperty(aWidget, "label"));
       let additionalTooltipArguments = [];
       if (aWidget.shortcutId) {
         let keyEl = aDocument.getElementById(aWidget.shortcutId);
         if (keyEl) {
           additionalTooltipArguments.push(ShortcutUtils.prettifyShortcut(keyEl));
         } else {
           ERROR("Key element with id '" + aWidget.shortcutId + "' for widget '" + aWidget.id +
                 "' not found!");
         }
       }
       let tooltip = this.getLocalizedProperty(aWidget, "tooltiptext", additionalTooltipArguments);
       node.setAttribute("tooltiptext", tooltip);
       node.setAttribute("class", "toolbarbutton-1 chromeclass-toolbar-additional");
       let commandHandler = this.handleWidgetCommand.bind(this, aWidget, node);
       node.addEventListener("command", commandHandler, false);
       let clickHandler = this.handleWidgetClick.bind(this, aWidget, node);
       node.addEventListener("click", clickHandler, false);
       // If the widget has a view, and has view showing / hiding listeners,
       // hook those up to this widget.
       if (aWidget.type == "view") {
         LOG("Widget " + aWidget.id + " has a view. Auto-registering event handlers.");
         let viewNode = aDocument.getElementById(aWidget.viewId);
         if (viewNode) {
           // PanelUI relies on the .PanelUI-subView class to be able to show only
           // one sub-view at a time.
           viewNode.classList.add("PanelUI-subView");
           for (let eventName of kSubviewEvents) {
             let handler = "on" + eventName;
             if (typeof aWidget[handler] == "function") {
               viewNode.addEventListener(eventName, aWidget[handler], false);
             }
           }
           LOG("Widget " + aWidget.id + " showing and hiding event handlers set.");
         } else {
           ERROR("Could not find the view node with id: " + aWidget.viewId +
                 ", for widget: " + aWidget.id + ".");
         }
       }
       if (aWidget.onCreated) {
         aWidget.onCreated(node);
       }
     }
     aWidget.instances.set(aDocument, node);
     return node;
   },
   getLocalizedProperty: function(aWidget, aProp, aFormatArgs, aDef) {
     if (typeof aWidget == "string") {
       aWidget = gPalette.get(aWidget);
     }
     if (!aWidget) {
       throw new Error("getLocalizedProperty was passed a non-widget to work with.");
     }
     let def, name;
     // Let widgets pass their own string identifiers or strings, so that
     // we can use strings which aren't the default (in case string ids change)
     // and so that non-builtin-widgets can also provide labels, tooltips, etc.
     if (aWidget[aProp]) {
       name = aWidget[aProp];
       // By using this as the default, if a widget provides a full string rather
       // than a string ID for localization, we will fall back to that string
       // and return that.
       def = aDef || name;
     } else {
       name = aWidget.id + "." + aProp;
       def = aDef || "";
     }
     try {
       if (Array.isArray(aFormatArgs) && aFormatArgs.length) {
         return gWidgetsBundle.formatStringFromName(name, aFormatArgs,
           aFormatArgs.length) || def;
       }
       return gWidgetsBundle.GetStringFromName(name) || def;
     } catch(ex) {
       if (!def) {
         ERROR("Could not localize property '" + name + "'.");
       }
     }
     return def;
   },
   handleWidgetCommand: function(aWidget, aNode, aEvent) {
     LOG("handleWidgetCommand");
     if (aWidget.type == "button") {
       if (aWidget.onCommand) {
         try {
           aWidget.onCommand.call(null, aEvent);
         } catch (e) {
           ERROR(e);
         }
       } else {
         //XXXunf Need to think this through more, and formalize.
         Services.obs.notifyObservers(aNode,
                                      "customizedui-widget-command",
                                      aWidget.id);
       }
     } else if (aWidget.type == "view") {
       let ownerWindow = aNode.ownerDocument.defaultView;
       let area = this.getPlacementOfWidget(aNode.id).area;
       let anchor = aNode;
       if (area != CustomizableUI.AREA_PANEL) {
         let wrapper = this.wrapWidget(aWidget.id).forWindow(ownerWindow);
         if (wrapper && wrapper.anchor) {
           this.hidePanelForNode(aNode);
           anchor = wrapper.anchor;
         }
       }
       ownerWindow.PanelUI.showSubView(aWidget.viewId, anchor, area);
     }
   },
   handleWidgetClick: function(aWidget, aNode, aEvent) {
     LOG("handleWidgetClick");
     if (aWidget.onClick) {
       try {
         aWidget.onClick.call(null, aEvent);
       } catch(e) {
         Cu.reportError(e);
       }
     } else {
       //XXXunf Need to think this through more, and formalize.
       Services.obs.notifyObservers(aNode, "customizedui-widget-click", aWidget.id);
     }
   },
   _getPanelForNode: function(aNode) {
     let panel = aNode;
     while (panel && panel.localName != "panel")
       panel = panel.parentNode;
     return panel;
   },
   /*
    * If people put things in the panel which need more than single-click interaction,
    * we don't want to close it. Right now we check for text inputs and menu buttons.
    * We also check for being outside of any toolbaritem/toolbarbutton, ie on a blank
    * part of the menu.
    */
   _isOnInteractiveElement: function(aEvent) {
     function getMenuPopupForDescendant(aNode) {
       let lastPopup = null;
       while (aNode && aNode.parentNode &&
              aNode.parentNode.localName.startsWith("menu")) {
         lastPopup = aNode.localName == "menupopup" ? aNode : lastPopup;
         aNode = aNode.parentNode;
       }
       return lastPopup;
     }
     let target = aEvent.originalTarget;
     let panel = this._getPanelForNode(aEvent.currentTarget);
     // This can happen in e.g. customize mode. If there's no panel,
     // there's clearly nothing for us to close; pretend we're interactive.
     if (!panel) {
       return true;
     }
     // We keep track of:
     // whether we're in an input container (text field)
     let inInput = false;
     // whether we're in a popup/context menu
     let inMenu = false;
     // whether we're in a toolbarbutton/toolbaritem
     let inItem = false;
     // whether the current menuitem has a valid closemenu attribute
     let menuitemCloseMenu = "auto";
     // whether the toolbarbutton/item has a valid closemenu attribute.
     let closemenu = "auto";
     // While keeping track of that, we go from the original target back up,
     // to the panel if we have to. We bail as soon as we find an input,
     // a toolbarbutton/item, or the panel:
     while (true && target) {
       let tagName = target.localName;
       inInput = tagName == "input" || tagName == "textbox";
       inItem = tagName == "toolbaritem" || tagName == "toolbarbutton";
       let isMenuItem = tagName == "menuitem";
       inMenu = inMenu || isMenuItem;
       if (inItem && target.hasAttribute("closemenu")) {
         let closemenuVal = target.getAttribute("closemenu");
         closemenu = (closemenuVal == "single" || closemenuVal == "none") ?
                     closemenuVal : "auto";
       }
       if (isMenuItem && target.hasAttribute("closemenu")) {
         let closemenuVal = target.getAttribute("closemenu");
         menuitemCloseMenu = (closemenuVal == "single" || closemenuVal == "none") ?
                             closemenuVal : "auto";
       }
       // This isn't in the loop condition because we want to break before
       // changing |target| if any of these conditions are true
       if (inInput || inItem || target == panel) {
         break;
       }
       // We need specific code for popups: the item on which they were invoked
       // isn't necessarily in their parentNode chain:
       if (isMenuItem) {
         let topmostMenuPopup = getMenuPopupForDescendant(target);
         target = (topmostMenuPopup && topmostMenuPopup.triggerNode) ||
                  target.parentNode;
       } else {
         target = target.parentNode;
       }
     }
     // If the user clicked a menu item...
     if (inMenu) {
       // We care if we're in an input also,
       // or if the user specified closemenu!="auto":
       if (inInput || menuitemCloseMenu != "auto") {
         return true;
       }
       // Otherwise, we're probably fine to close the panel
       return false;
     }
     // If we're not in a menu, and we *are* in a type="menu" toolbarbutton,
     // we'll now interact with the menu
     if (inItem && target.getAttribute("type") == "menu") {
       return true;
     }
     // If we're not in a menu, and we *are* in a type="menu-button" toolbarbutton,
     // it depends whether we're in the dropmarker or the 'real' button:
     if (inItem && target.getAttribute("type") == "menu-button") {
       // 'real' button (which has a single action):
       if (target.getAttribute("anonid") == "button") {
         return closemenu != "none";
       }
       // otherwise, this is the outer button, and the user will now
       // interact with the menu:
       return true;
     }
     return inInput || !inItem;
   },
   hidePanelForNode: function(aNode) {
     let panel = this._getPanelForNode(aNode);
     if (panel) {
       panel.hidePopup();
     }
   },
   maybeAutoHidePanel: function(aEvent) {
     if (aEvent.type == "keypress") {
       if (aEvent.keyCode != aEvent.DOM_VK_RETURN) {
         return;
       }
       // If the user hit enter/return, we don't check preventDefault - it makes sense
       // that this was prevented, but we probably still want to close the panel.
       // If consumers don't want this to happen, they should specify the closemenu
       // attribute.
     } else if (aEvent.type != "command") { // mouse events:
       if (aEvent.defaultPrevented || aEvent.button != 0) {
         return;
       }
       let isInteractive = this._isOnInteractiveElement(aEvent);
       LOG("maybeAutoHidePanel: interactive ? " + isInteractive);
       if (isInteractive) {
         return;
       }
     }
     // We can't use event.target because we might have passed a panelview
     // anonymous content boundary as well, and so target points to the
     // panelmultiview in that case. Unfortunately, this means we get
     // anonymous child nodes instead of the real ones, so looking for the
     // 'stoooop, don't close me' attributes is more involved.
     let target = aEvent.originalTarget;
     let closemenu = "auto";
     let widgetType = "button";
     while (target.parentNode && target.localName != "panel") {
       closemenu = target.getAttribute("closemenu");
       widgetType = target.getAttribute("widget-type");
       if (closemenu == "none" || closemenu == "single" ||
           widgetType == "view") {
         break;
       }
       target = target.parentNode;
     }
     if (closemenu == "none" || widgetType == "view") {
       return;
     }
     if (closemenu == "single") {
       let panel = this._getPanelForNode(target);
       let multiview = panel.querySelector("panelmultiview");
       if (multiview.showingSubView) {
         multiview.showMainView();
         return;
       }
     }
     // If we get here, we can actually hide the popup:
     this.hidePanelForNode(aEvent.target);
   },
   getUnusedWidgets: function(aWindowPalette) {
     let window = aWindowPalette.ownerDocument.defaultView;
     let isWindowPrivate = PrivateBrowsingUtils.isWindowPrivate(window);
     // We use a Set because there can be overlap between the widgets in
     // gPalette and the items in the palette, especially after the first
     // customization, since programmatically generated widgets will remain
     // in the toolbox palette.
     let widgets = new Set();
     // It's possible that some widgets have been defined programmatically and
     // have not been overlayed into the palette. We can find those inside
     // gPalette.
     for (let [id, widget] of gPalette) {
       if (!widget.currentArea) {
         if (widget.showInPrivateBrowsing || !isWindowPrivate) {
           widgets.add(id);
         }
       }
     }
     LOG("Iterating the actual nodes of the window palette");
     for (let node of aWindowPalette.children) {
       LOG("In palette children: " + node.id);
       if (node.id && !this.getPlacementOfWidget(node.id)) {
         widgets.add(node.id);
       }
     }
     return [...widgets];
   },
   getPlacementOfWidget: function(aWidgetId, aOnlyRegistered, aDeadAreas) {
     if (aOnlyRegistered && !this.widgetExists(aWidgetId)) {
       return null;
     }
     for (let [area, placements] of gPlacements) {
       if (!gAreas.has(area) && !aDeadAreas) {
         continue;
       }
       let index = placements.indexOf(aWidgetId);
       if (index != -1) {
         return { area: area, position: index };
       }
     }
     return null;
   },
   widgetExists: function(aWidgetId) {
     if (gPalette.has(aWidgetId) || this.isSpecialWidget(aWidgetId)) {
       return true;
     }
     // Destroyed API widgets are in gSeenWidgets, but not in gPalette:
     if (gSeenWidgets.has(aWidgetId)) {
       return false;
     }
     // We're assuming XUL widgets always exist, as it's much harder to check,
     // and checking would be much more error prone.
     return true;
   },
   addWidgetToArea: function(aWidgetId, aArea, aPosition, aInitialAdd) {
     if (!gAreas.has(aArea)) {
       throw new Error("Unknown customization area: " + aArea);
     }
     // Hack: don't want special widgets in the panel (need to check here as well
     // as in canWidgetMoveToArea because the menu panel is lazy):
     if (gAreas.get(aArea).get("type") == CustomizableUI.TYPE_MENU_PANEL &&
         this.isSpecialWidget(aWidgetId)) {
       return;
     }
     // If this is a lazy area that hasn't been restored yet, we can't yet modify
     // it - would would at least like to add to it. So we keep track of it in
     // gFuturePlacements,  and use that to add it when restoring the area. We
     // throw away aPosition though, as that can only be bogus if the area hasn't
     // yet been restorted (caller can't possibly know where its putting the
     // widget in relation to other widgets).
     if (this.isAreaLazy(aArea)) {
       gFuturePlacements.get(aArea).add(aWidgetId);
       return;
     }
     if (this.isSpecialWidget(aWidgetId)) {
       aWidgetId = this.ensureSpecialWidgetId(aWidgetId);
     }
     let oldPlacement = this.getPlacementOfWidget(aWidgetId, false, true);
     if (oldPlacement && oldPlacement.area == aArea) {
       this.moveWidgetWithinArea(aWidgetId, aPosition);
       return;
     }
     // Do nothing if the widget is not allowed to move to the target area.
     if (!this.canWidgetMoveToArea(aWidgetId, aArea)) {
       return;
     }
     if (oldPlacement) {
       this.removeWidgetFromArea(aWidgetId);
     }
     if (!gPlacements.has(aArea)) {
       gPlacements.set(aArea, [aWidgetId]);
       aPosition = 0;
     } else {
       let placements = gPlacements.get(aArea);
       if (typeof aPosition != "number") {
         aPosition = placements.length;
       }
       if (aPosition < 0) {
         aPosition = 0;
       }
       placements.splice(aPosition, 0, aWidgetId);
     }
     let widget = gPalette.get(aWidgetId);
     if (widget) {
       widget.currentArea = aArea;
       widget.currentPosition = aPosition;
     }
     // We initially set placements with addWidgetToArea, so in that case
     // we don't consider the area "dirtied".
     if (!aInitialAdd) {
       gDirtyAreaCache.add(aArea);
     }
     gDirty = true;
     this.saveState();
     this.notifyListeners("onWidgetAdded", aWidgetId, aArea, aPosition);
   },
   removeWidgetFromArea: function(aWidgetId) {
     let oldPlacement = this.getPlacementOfWidget(aWidgetId, false, true);
     if (!oldPlacement) {
       return;
     }
     if (!this.isWidgetRemovable(aWidgetId)) {
       return;
     }
     let placements = gPlacements.get(oldPlacement.area);
     let position = placements.indexOf(aWidgetId);
     if (position != -1) {
       placements.splice(position, 1);
     }
     let widget = gPalette.get(aWidgetId);
     if (widget) {
       widget.currentArea = null;
       widget.currentPosition = null;
     }
     gDirty = true;
     this.saveState();
     gDirtyAreaCache.add(oldPlacement.area);
     this.notifyListeners("onWidgetRemoved", aWidgetId, oldPlacement.area);
   },
   moveWidgetWithinArea: function(aWidgetId, aPosition) {
     let oldPlacement = this.getPlacementOfWidget(aWidgetId);
     if (!oldPlacement) {
       return;
     }
     let placements = gPlacements.get(oldPlacement.area);
     if (typeof aPosition != "number") {
       aPosition = placements.length;
     } else if (aPosition < 0) {
       aPosition = 0;
     } else if (aPosition > placements.length) {
       aPosition = placements.length;
     }
     let widget = gPalette.get(aWidgetId);
     if (widget) {
       widget.currentPosition = aPosition;
       widget.currentArea = oldPlacement.area;
     }
     if (aPosition == oldPlacement.position) {
       return;
     }
     placements.splice(oldPlacement.position, 1);
     // If we just removed the item from *before* where it is now added,
     // we need to compensate the position offset for that:
     if (oldPlacement.position < aPosition) {
       aPosition--;
     }
     placements.splice(aPosition, 0, aWidgetId);
     gDirty = true;
     gDirtyAreaCache.add(oldPlacement.area);
     this.saveState();
     this.notifyListeners("onWidgetMoved", aWidgetId, oldPlacement.area,
                          oldPlacement.position, aPosition);
   },
   // Note that this does not populate gPlacements, which is done lazily so that
   // the legacy state can be migrated, which is only available once a browser
   // window is openned.
   // The panel area is an exception here, since it has no legacy state and is
   // built lazily - and therefore wouldn't otherwise result in restoring its
   // state immediately when a browser window opens, which is important for
   // other consumers of this API.
   loadSavedState: function() {
     let state = null;
     try {
       state = Services.prefs.getCharPref(kPrefCustomizationState);
     } catch (e) {
       LOG("No saved state found");
       // This will fail if nothing has been customized, so silently fall back to
       // the defaults.
     }
     if (!state) {
       return;
     }
     try {
       gSavedState = JSON.parse(state);
       if (typeof gSavedState != "object" || gSavedState === null) {
         throw "Invalid saved state";
       }
     } catch(e) {
       Services.prefs.clearUserPref(kPrefCustomizationState);
       gSavedState = {};
       LOG("Error loading saved UI customization state, falling back to defaults.");
     }
     if (!("placements" in gSavedState)) {
       gSavedState.placements = {};
     }
     gSeenWidgets = new Set(gSavedState.seen || []);
     gDirtyAreaCache = new Set(gSavedState.dirtyAreaCache || []);
     gNewElementCount = gSavedState.newElementCount || 0;
   },
   restoreStateForArea: function(aArea, aLegacyState) {
     let placementsPreexisted = gPlacements.has(aArea);
     this.beginBatchUpdate();
     try {
       gRestoring = true;
       let restored = false;
       if (placementsPreexisted) {
         LOG("Restoring " + aArea + " from pre-existing placements");
         for (let [position, id] in Iterator(gPlacements.get(aArea))) {
           this.moveWidgetWithinArea(id, position);
         }
         gDirty = false;
         restored = true;
       } else {
         gPlacements.set(aArea, []);
       }
       if (!restored && gSavedState && aArea in gSavedState.placements) {
         LOG("Restoring " + aArea + " from saved state");
         let placements = gSavedState.placements[aArea];
         for (let id of placements)
           this.addWidgetToArea(id, aArea);
         gDirty = false;
         restored = true;
       }
       if (!restored && aLegacyState) {
         LOG("Restoring " + aArea + " from legacy state");
         for (let id of aLegacyState)
           this.addWidgetToArea(id, aArea);
         // Don't override dirty state, to ensure legacy state is saved here and
         // therefore only used once.
         restored = true;
       }
       if (!restored) {
         LOG("Restoring " + aArea + " from default state");
         let defaults = gAreas.get(aArea).get("defaultPlacements");
         if (defaults) {
           for (let id of defaults)
             this.addWidgetToArea(id, aArea, null, true);
         }
         gDirty = false;
       }
       // Finally, add widgets to the area that were added before the it was able
       // to be restored. This can occur when add-ons register widgets for a
       // lazily-restored area before it's been restored.
       if (gFuturePlacements.has(aArea)) {
         for (let id of gFuturePlacements.get(aArea))
           this.addWidgetToArea(id, aArea);
       }
       LOG("Placements for " + aArea + ":\n\t" + gPlacements.get(aArea).join("\n\t"));
       gRestoring = false;
     } finally {
       this.endBatchUpdate();
     }
   },
   saveState: function() {
     if (gInBatchStack || !gDirty) {
       return;
     }
     let state = { placements: gPlacements,
                   seen: gSeenWidgets,
                   dirtyAreaCache: gDirtyAreaCache,
                   newElementCount: gNewElementCount };
     LOG("Saving state.");
     let serialized = JSON.stringify(state, this.serializerHelper);
     LOG("State saved as: " + serialized);
     Services.prefs.setCharPref(kPrefCustomizationState, serialized);
     gDirty = false;
   },
   serializerHelper: function(aKey, aValue) {
     if (typeof aValue == "object" && aValue.constructor.name == "Map") {
       let result = {};
       for (let [mapKey, mapValue] of aValue)
         result[mapKey] = mapValue;
       return result;
     }
     if (typeof aValue == "object" && aValue.constructor.name == "Set") {
       return [...aValue];
     }
     return aValue;
   },
   beginBatchUpdate: function() {
     gInBatchStack++;
   },
   endBatchUpdate: function(aForceDirty) {
     gInBatchStack--;
     if (aForceDirty === true) {
       gDirty = true;
     }
     if (gInBatchStack == 0) {
       this.saveState();
     } else if (gInBatchStack < 0) {
       throw new Error("The batch editing stack should never reach a negative number.");
     }
   },
   addListener: function(aListener) {
     gListeners.add(aListener);
   },
   removeListener: function(aListener) {
     if (aListener == this) {
       return;
     }
     gListeners.delete(aListener);
   },
   notifyListeners: function(aEvent, ...aArgs) {
     if (gRestoring) {
       return;
     }
     for (let listener of gListeners) {
       try {
         if (typeof listener[aEvent] == "function") {
           listener[aEvent].apply(listener, aArgs);
         }
       } catch (e) {
         ERROR(e + " -- " + e.fileName + ":" + e.lineNumber);
       }
     }
   },
   _dispatchToolboxEventToWindow: function(aEventType, aDetails, aWindow) {
     let evt = new aWindow.CustomEvent(aEventType, {
       bubbles: true,
       cancelable: true,
       detail: aDetails
     });
     aWindow.gNavToolbox.dispatchEvent(evt);
   },
   dispatchToolboxEvent: function(aEventType, aDetails={}, aWindow=null) {
     if (aWindow) {
       return this._dispatchToolboxEventToWindow(aEventType, aDetails, aWindow);
     }
     for (let [win, ] of gBuildWindows) {
       this._dispatchToolboxEventToWindow(aEventType, aDetails, win);
     }
   },
   createWidget: function(aProperties) {
     let widget = this.normalizeWidget(aProperties, CustomizableUI.SOURCE_EXTERNAL);
     //XXXunf This should probably throw.
     if (!widget) {
       return;
     }
     gPalette.set(widget.id, widget);
     // Clear our caches:
     gGroupWrapperCache.delete(widget.id);
     for (let [win, ] of gBuildWindows) {
       let cache = gSingleWrapperCache.get(win);
       if (cache) {
         cache.delete(widget.id);
       }
     }
     this.notifyListeners("onWidgetCreated", widget.id);
     if (widget.defaultArea) {
       let area = gAreas.get(widget.defaultArea);
       //XXXgijs this won't have any effect for legacy items. Sort of OK because
       // consumers can modify currentset? Maybe?
       if (area.has("defaultPlacements")) {
         area.get("defaultPlacements").push(widget.id);
       } else {
         area.set("defaultPlacements", [widget.id]);
       }
     }
     // Look through previously saved state to see if we're restoring a widget.
     let seenAreas = new Set();
     let widgetMightNeedAutoAdding = true;
     for (let [area, placements] of gPlacements) {
       seenAreas.add(area);
       let areaIsRegistered = gAreas.has(area);
       let index = gPlacements.get(area).indexOf(widget.id);
       if (index != -1) {
         widgetMightNeedAutoAdding = false;
         if (areaIsRegistered) {
           widget.currentArea = area;
           widget.currentPosition = index;
         }
         break;
       }
     }
     // Also look at saved state data directly in areas that haven't yet been
     // restored. Can't rely on this for restored areas, as they may have
     // changed.
     if (widgetMightNeedAutoAdding && gSavedState) {
       for (let area of Object.keys(gSavedState.placements)) {
         if (seenAreas.has(area)) {
           continue;
         }
         let areaIsRegistered = gAreas.has(area);
         let index = gSavedState.placements[area].indexOf(widget.id);
         if (index != -1) {
           widgetMightNeedAutoAdding = false;
           if (areaIsRegistered) {
             widget.currentArea = area;
             widget.currentPosition = index;
           }
           break;
         }
       }
     }
     // If we're restoring the widget to it's old placement, fire off the
     // onWidgetAdded event - our own handler will take care of adding it to
     // any build areas.
     if (widget.currentArea) {
       this.notifyListeners("onWidgetAdded", widget.id, widget.currentArea,
                            widget.currentPosition);
     } else if (widgetMightNeedAutoAdding) {
       let autoAdd = true;
       try {
         autoAdd = Services.prefs.getBoolPref(kPrefCustomizationAutoAdd);
       } catch (e) {}
       // If the widget doesn't have an existing placement, and it hasn't been
       // seen before, then add it to its default area so it can be used.
       // If the widget is not removable, we *have* to add it to its default
       // area here.
       let canBeAutoAdded = autoAdd && !gSeenWidgets.has(widget.id);
       if (!widget.currentArea && (!widget.removable || canBeAutoAdded)) {
         this.beginBatchUpdate();
         try {
           gSeenWidgets.add(widget.id);
           if (widget.defaultArea) {
             if (this.isAreaLazy(widget.defaultArea)) {
               gFuturePlacements.get(widget.defaultArea).add(widget.id);
             } else {
               this.addWidgetToArea(widget.id, widget.defaultArea);
             }
           }
         } finally {
           this.endBatchUpdate(true);
         }
       }
     }
     this.notifyListeners("onWidgetAfterCreation", widget.id, widget.currentArea);
     return widget.id;
   },
   createBuiltinWidget: function(aData) {
     // This should only ever be called on startup, before any windows are
     // opened - so we know there's no build areas to handle. Also, builtin
     // widgets are expected to be (mostly) static, so shouldn't affect the
     // current placement settings.
     let widget = this.normalizeWidget(aData, CustomizableUI.SOURCE_BUILTIN);
     if (!widget) {
       ERROR("Error creating builtin widget: " + aData.id);
       return;
     }
     LOG("Creating built-in widget with id: " + widget.id);
     gPalette.set(widget.id, widget);
   },
   // Returns true if the area will eventually lazily restore (but hasn't yet).
   isAreaLazy: function(aArea) {
     if (gPlacements.has(aArea)) {
       return false;
     }
     return gAreas.get(aArea).has("legacy");
   },
   //XXXunf Log some warnings here, when the data provided isn't up to scratch.
   normalizeWidget: function(aData, aSource) {
     let widget = {
       implementation: aData,
       source: aSource || "addon",
       instances: new Map(),
       currentArea: null,
       removable: true,
       overflows: true,
       defaultArea: null,
       shortcutId: null,
       tooltiptext: null,
       showInPrivateBrowsing: true,
     };
     if (typeof aData.id != "string" || !/^[a-z0-9-_]{1,}$/i.test(aData.id)) {
       ERROR("Given an illegal id in normalizeWidget: " + aData.id);
       return null;
     }
     delete widget.implementation.currentArea;
     widget.implementation.__defineGetter__("currentArea", function() widget.currentArea);
     const kReqStringProps = ["id"];
     for (let prop of kReqStringProps) {
       if (typeof aData[prop] != "string") {
         ERROR("Missing required property '" + prop + "' in normalizeWidget: "
               + aData.id);
         return null;
       }
       widget[prop] = aData[prop];
     }
     const kOptStringProps = ["label", "tooltiptext", "shortcutId"];
     for (let prop of kOptStringProps) {
       if (typeof aData[prop] == "string") {
         widget[prop] = aData[prop];
       }
     }
     const kOptBoolProps = ["removable", "showInPrivateBrowsing", "overflows"];
     for (let prop of kOptBoolProps) {
       if (typeof aData[prop] == "boolean") {
         widget[prop] = aData[prop];
       }
     }
     if (aData.defaultArea && gAreas.has(aData.defaultArea)) {
       widget.defaultArea = aData.defaultArea;
     } else if (!widget.removable) {
       ERROR("Widget '" + widget.id + "' is not removable but does not specify " +
             "a valid defaultArea. That's not possible; it must specify a " +
             "valid defaultArea as well.");
       return null;
     }
     if ("type" in aData && gSupportedWidgetTypes.has(aData.type)) {
       widget.type = aData.type;
     } else {
       widget.type = "button";
     }
     widget.disabled = aData.disabled === true;
     this.wrapWidgetEventHandler("onBeforeCreated", widget);
     this.wrapWidgetEventHandler("onClick", widget);
     this.wrapWidgetEventHandler("onCreated", widget);
     if (widget.type == "button") {
       widget.onCommand = typeof aData.onCommand == "function" ?
                            aData.onCommand :
                            null;
     } else if (widget.type == "view") {
       if (typeof aData.viewId != "string") {
         ERROR("Expected a string for widget " + widget.id + " viewId, but got "
               + aData.viewId);
         return null;
       }
       widget.viewId = aData.viewId;
       this.wrapWidgetEventHandler("onViewShowing", widget);
       this.wrapWidgetEventHandler("onViewHiding", widget);
     } else if (widget.type == "custom") {
       this.wrapWidgetEventHandler("onBuild", widget);
     }
     if (gPalette.has(widget.id)) {
       return null;
     }
     return widget;
   },
   wrapWidgetEventHandler: function(aEventName, aWidget) {
     if (typeof aWidget.implementation[aEventName] != "function") {
       aWidget[aEventName] = null;
       return;
     }
     aWidget[aEventName] = function(...aArgs) {
       // Wrap inside a try...catch to properly log errors, until bug 862627 is
       // fixed, which in turn might help bug 503244.
       try {
         // Don't copy the function to the normalized widget object, instead
         // keep it on the original object provided to the API so that
         // additional methods can be implemented and used by the event
         // handlers.
         return aWidget.implementation[aEventName].apply(aWidget.implementation,
                                                         aArgs);
       } catch (e) {
         Cu.reportError(e);
       }
     };
   },
   destroyWidget: function(aWidgetId) {
     let widget = gPalette.get(aWidgetId);
     if (!widget) {
       gGroupWrapperCache.delete(aWidgetId);
       for (let [window, ] of gBuildWindows) {
         let windowCache = gSingleWrapperCache.get(window);
         if (windowCache) {
           windowCache.delete(aWidgetId);
         }
       }
       return;
     }
     // Remove it from the default placements of an area if it was added there:
     if (widget.defaultArea) {
       let area = gAreas.get(widget.defaultArea);
       if (area) {
         let defaultPlacements = area.get("defaultPlacements");
         // We can assume this is present because if a widget has a defaultArea,
         // we automatically create a defaultPlacements array for that area.
         let widgetIndex = defaultPlacements.indexOf(aWidgetId);
         if (widgetIndex != -1) {
           defaultPlacements.splice(widgetIndex, 1);
         }
       }
     }
     // This will not remove the widget from gPlacements - we want to keep the
     // setting so the widget gets put back in it's old position if/when it
     // returns.
     for (let [window, ] of gBuildWindows) {
       let windowCache = gSingleWrapperCache.get(window);
       if (windowCache) {
         windowCache.delete(aWidgetId);
       }
       let widgetNode = window.document.getElementById(aWidgetId) ||
                        window.gNavToolbox.palette.getElementsByAttribute("id", aWidgetId)[0];
       if (widgetNode) {
         let container = widgetNode.parentNode
         this.notifyListeners("onWidgetBeforeDOMChange", widgetNode, null,
                              container, true);
         widgetNode.remove();
         this.notifyListeners("onWidgetAfterDOMChange", widgetNode, null,
                              container, true);
       }
       if (widget.type == "view") {
         let viewNode = window.document.getElementById(widget.viewId);
         if (viewNode) {
           for (let eventName of kSubviewEvents) {
             let handler = "on" + eventName;
             if (typeof widget[handler] == "function") {
               viewNode.removeEventListener(eventName, widget[handler], false);
             }
           }
         }
       }
     }
     gPalette.delete(aWidgetId);
     gGroupWrapperCache.delete(aWidgetId);
     this.notifyListeners("onWidgetDestroyed", aWidgetId);
   },
   getCustomizeTargetForArea: function(aArea, aWindow) {
     let buildAreaNodes = gBuildAreas.get(aArea);
     if (!buildAreaNodes) {
       return null;
     }
     for (let node of buildAreaNodes) {
       if (node.ownerDocument.defaultView === aWindow) {
         return node.customizationTarget ? node.customizationTarget : node;
       }
     }
     return null;
   },
   reset: function() {
     gResetting = true;
     this._resetUIState();
     // Rebuild each registered area (across windows) to reflect the state that
     // was reset above.
     this._rebuildRegisteredAreas();
     gResetting = false;
   },
   _resetUIState: function() {
     try {
       gUIStateBeforeReset.drawInTitlebar = Services.prefs.getBoolPref(kPrefDrawInTitlebar);
       gUIStateBeforeReset.uiCustomizationState = Services.prefs.getCharPref(kPrefCustomizationState);
     } catch(e) { }
     this._resetExtraToolbars();
     Services.prefs.clearUserPref(kPrefCustomizationState);
     Services.prefs.clearUserPref(kPrefDrawInTitlebar);
     LOG("State reset");
     // Reset placements to make restoring default placements possible.
     gPlacements = new Map();
     gDirtyAreaCache = new Set();
     gSeenWidgets = new Set();
     // Clear the saved state to ensure that defaults will be used.
     gSavedState = null;
     // Restore the state for each area to its defaults
     for (let [areaId,] of gAreas) {
       this.restoreStateForArea(areaId);
     }
   },
   _resetExtraToolbars: function(aFilter = null) {
     let firstWindow = true; // Only need to unregister and persist once
     for (let [win, ] of gBuildWindows) {
       let toolbox = win.gNavToolbox;
       for (let child of toolbox.children) {
         let matchesFilter = !aFilter || aFilter == child.id;
         if (child.hasAttribute("customindex") && matchesFilter) {
           let toolbarId = "toolbar" + child.getAttribute("customindex");
           toolbox.toolbarset.removeAttribute(toolbarId);
           if (firstWindow) {
             win.document.persist(toolbox.toolbarset.id, toolbarId);
             // We have to unregister it properly to ensure we don't kill
             // XUL widgets which might be in here
             this.unregisterArea(child.id, true);
           }
           child.remove();
         }
       }
       firstWindow = false;
     }
   },
   _rebuildRegisteredAreas: function() {
     for (let [areaId, areaNodes] of gBuildAreas) {
       let placements = gPlacements.get(areaId);
       let isFirstChangedToolbar = true;
       for (let areaNode of areaNodes) {
         this.buildArea(areaId, placements, areaNode);
         let area = gAreas.get(areaId);
         if (area.get("type") == CustomizableUI.TYPE_TOOLBAR) {
           let defaultCollapsed = area.get("defaultCollapsed");
           let win = areaNode.ownerDocument.defaultView;
           if (defaultCollapsed !== null) {
             win.setToolbarVisibility(areaNode, !defaultCollapsed, isFirstChangedToolbar);
           }
         }
         isFirstChangedToolbar = false;
       }
     }
   },
   /**
    * Undoes a previous reset, restoring the state of the UI to the state prior to the reset.
    */
   undoReset: function() {
     if (gUIStateBeforeReset.uiCustomizationState == null ||
         gUIStateBeforeReset.drawInTitlebar == null) {
       return;
     }
     gUndoResetting = true;
     let uiCustomizationState = gUIStateBeforeReset.uiCustomizationState;
     let drawInTitlebar = gUIStateBeforeReset.drawInTitlebar;
     // Need to clear the previous state before setting the prefs
     // because pref observers may check if there is a previous UI state.
     this._clearPreviousUIState();
     Services.prefs.setCharPref(kPrefCustomizationState, uiCustomizationState);
     Services.prefs.setBoolPref(kPrefDrawInTitlebar, drawInTitlebar);
     this.loadSavedState();
     // If the user just customizes toolbar/titlebar visibility, gSavedState will be null
     // and we don't need to do anything else here:
     if (gSavedState) {
       for (let areaId of Object.keys(gSavedState.placements)) {
         let placements = gSavedState.placements[areaId];
         gPlacements.set(areaId, placements);
       }
       this._rebuildRegisteredAreas();
     }
     gUndoResetting = false;
   },
   _clearPreviousUIState: function() {
     Object.getOwnPropertyNames(gUIStateBeforeReset).forEach((prop) => {
       gUIStateBeforeReset[prop] = null;
     });
   },
   removeExtraToolbar: function(aToolbarId) {
     this._resetExtraToolbars(aToolbarId);
   },
   /**
    * @param {String|Node} aWidget - widget ID or a widget node (preferred for performance).
    * @return {Boolean} whether the widget is removable
    */
   isWidgetRemovable: function(aWidget) {
     let widgetId;
     let widgetNode;
     if (typeof aWidget == "string") {
       widgetId = aWidget;
     } else {
       widgetId = aWidget.id;
       widgetNode = aWidget;
     }
     let provider = this.getWidgetProvider(widgetId);
     if (provider == CustomizableUI.PROVIDER_API) {
       return gPalette.get(widgetId).removable;
     }
     if (provider == CustomizableUI.PROVIDER_XUL) {
       if (gBuildWindows.size == 0) {
         // We don't have any build windows to look at, so just assume for now
         // that its removable.
         return true;
       }
       if (!widgetNode) {
         // Pick any of the build windows to look at.
         let [window,] = [...gBuildWindows][0];
         [, widgetNode] = this.getWidgetNode(widgetId, window);
       }
       // If we don't have a node, we assume it's removable. This can happen because
       // getWidgetProvider returns PROVIDER_XUL by default, but this will also happen
       // for API-provided widgets which have been destroyed.
       if (!widgetNode) {
         return true;
       }
       return widgetNode.getAttribute("removable") == "true";
     }
     // Otherwise this is either a special widget, which is always removable, or
     // an API widget which has already been removed from gPalette. Returning true
     // here allows us to then remove its ID from any placements where it might
     // still occur.
     return true;
   },
   canWidgetMoveToArea: function(aWidgetId, aArea) {
     let placement = this.getPlacementOfWidget(aWidgetId);
     if (placement && placement.area != aArea) {
       // Special widgets can't move to the menu panel.
       if (this.isSpecialWidget(aWidgetId) && gAreas.has(aArea) &&
           gAreas.get(aArea).get("type") == CustomizableUI.TYPE_MENU_PANEL) {
         return false;
       }
       // For everything else, just return whether the widget is removable.
       return this.isWidgetRemovable(aWidgetId);
     }
     return true;
   },
   ensureWidgetPlacedInWindow: function(aWidgetId, aWindow) {
     let placement = this.getPlacementOfWidget(aWidgetId);
     if (!placement) {
       return false;
     }
     let areaNodes = gBuildAreas.get(placement.area);
     if (!areaNodes) {
       return false;
     }
     let container = [...areaNodes].filter((n) => n.ownerDocument.defaultView == aWindow);
     if (!container.length) {
       return false;
     }
     let existingNode = container[0].getElementsByAttribute("id", aWidgetId)[0];
     if (existingNode) {
       return true;
     }
     this.insertNodeInWindow(aWidgetId, container[0], true);
     return true;
   },
   get inDefaultState() {
     for (let [areaId, props] of gAreas) {
       let defaultPlacements = props.get("defaultPlacements");
       // Areas without default placements (like legacy ones?) get skipped
       if (!defaultPlacements) {
         continue;
       }
       let currentPlacements = gPlacements.get(areaId);
       // We're excluding all of the placement IDs for items that do not exist,
       // and items that have removable="false",
       // because we don't want to consider them when determining if we're
       // in the default state. This way, if an add-on introduces a widget
       // and is then uninstalled, the leftover placement doesn't cause us to
       // automatically assume that the buttons are not in the default state.
       let buildAreaNodes = gBuildAreas.get(areaId);
       if (buildAreaNodes && buildAreaNodes.size) {
         let container = [...buildAreaNodes][0];
         let removableOrDefault = (itemNodeOrItem) => {
           let item = (itemNodeOrItem && itemNodeOrItem.id) || itemNodeOrItem;
           let isRemovable = this.isWidgetRemovable(itemNodeOrItem);
           let isInDefault = defaultPlacements.indexOf(item) != -1;
           return isRemovable || isInDefault;
         };
         // Toolbars have a currentSet property which also deals correctly with overflown
         // widgets (if any) - use that instead:
         if (props.get("type") == CustomizableUI.TYPE_TOOLBAR) {
           let currentSet = container.currentSet;
           currentPlacements = currentSet ? currentSet.split(',') : [];
           currentPlacements = currentPlacements.filter(removableOrDefault);
         } else {
           // Clone the array so we don't modify the actual placements...
           currentPlacements = [...currentPlacements];
           currentPlacements = currentPlacements.filter((item) => {
             let itemNode = container.getElementsByAttribute("id", item)[0];
             return itemNode && removableOrDefault(itemNode || item);
           });
         }
         if (props.get("type") == CustomizableUI.TYPE_TOOLBAR) {
           let attribute = container.getAttribute("type") == "menubar" ? "autohide" : "collapsed";
           let collapsed = container.getAttribute(attribute) == "true";
           let defaultCollapsed = props.get("defaultCollapsed");
           if (defaultCollapsed !== null && collapsed != defaultCollapsed) {
             LOG("Found " + areaId + " had non-default toolbar visibility (expected " + defaultCollapsed + ", was " + collapsed + ")");
             return false;
           }
         }
       }
       LOG("Checking default state for " + areaId + ":\n" + currentPlacements.join(",") +
           "\nvs.\n" + defaultPlacements.join(","));
       if (currentPlacements.length != defaultPlacements.length) {
         return false;
       }
       for (let i = 0; i < currentPlacements.length; ++i) {
         if (currentPlacements[i] != defaultPlacements[i]) {
           LOG("Found " + currentPlacements[i] + " in " + areaId + " where " +
               defaultPlacements[i] + " was expected!");
           return false;
         }
       }
     }
     if (Services.prefs.prefHasUserValue(kPrefDrawInTitlebar)) {
       LOG(kPrefDrawInTitlebar + " pref is non-default");
       return false;
     }
     return true;
   },
   setToolbarVisibility: function(aToolbarId, aIsVisible) {
     // We only persist the attribute the first time.
     let isFirstChangedToolbar = true;
     for (let window of CustomizableUI.windows) {
       let toolbar = window.document.getElementById(aToolbarId);
       if (toolbar) {
         window.setToolbarVisibility(toolbar, aIsVisible, isFirstChangedToolbar);
         isFirstChangedToolbar = false;
       }
     }
   },
 };
 Object.freeze(CustomizableUIInternal);
 this.CustomizableUI = {
   /**
    * Constant reference to the ID of the menu panel.
    */
   get AREA_PANEL() "PanelUI-contents",
   /**
    * Constant reference to the ID of the navigation toolbar.
    */
   get AREA_NAVBAR() "nav-bar",
   /**
    * Constant reference to the ID of the menubar's toolbar.
    */
   get AREA_MENUBAR() "toolbar-menubar",
   /**
    * Constant reference to the ID of the tabstrip toolbar.
    */
   get AREA_TABSTRIP() "TabsToolbar",
   /**
    * Constant reference to the ID of the bookmarks toolbar.
    */
   get AREA_BOOKMARKS() "PersonalToolbar",
   /**
    * Constant reference to the ID of the addon-bar toolbar shim.
    * Do not use, this will be removed as soon as reasonably possible.
    * @deprecated
    */
   get AREA_ADDONBAR() "addon-bar",
   /**
    * Constant indicating the area is a menu panel.
    */
   get TYPE_MENU_PANEL() "menu-panel",
   /**
    * Constant indicating the area is a toolbar.
    */
   get TYPE_TOOLBAR() "toolbar",
   /**
    * Constant indicating a XUL-type provider.
    */
   get PROVIDER_XUL() "xul",
   /**
    * Constant indicating an API-type provider.
    */
   get PROVIDER_API() "api",
   /**
    * Constant indicating dynamic (special) widgets: spring, spacer, and separator.
    */
   get PROVIDER_SPECIAL() "special",
   /**
    * Constant indicating the widget is built-in
    */
   get SOURCE_BUILTIN() "builtin",
   /**
    * Constant indicating the widget is externally provided
    * (e.g. by add-ons or other items not part of the builtin widget set).
    */
   get SOURCE_EXTERNAL() "external",
   /**
    * The class used to distinguish items that span the entire menu panel.
    */
   get WIDE_PANEL_CLASS() "panel-wide-item",
   /**
    * The (constant) number of columns in the menu panel.
    */
   get PANEL_COLUMN_COUNT() 3,
   /**
    * Constant indicating the reason the event was fired was a window closing
    */
   get REASON_WINDOW_CLOSED() "window-closed",
   /**
    * Constant indicating the reason the event was fired was an area being
    * unregistered separately from window closing mechanics.
    */
   get REASON_AREA_UNREGISTERED() "area-unregistered",
   /**
    * An iteratable property of windows managed by CustomizableUI.
    * Note that this can *only* be used as an iterator. ie:
    *     for (let window of CustomizableUI.windows) { ... }
    */
   windows: {
     "@@iterator": function*() {
       for (let [window,] of gBuildWindows)
         yield window;
     }
   },
   /**
    * Add a listener object that will get fired for various events regarding
    * customization.
    *
    * @param aListener the listener object to add
    *
    * Not all event handler methods need to be defined.
    * CustomizableUI will catch exceptions. Events are dispatched
    * synchronously on the UI thread, so if you can delay any/some of your
    * processing, that is advisable. The following event handlers are supported:
    *   - onWidgetAdded(aWidgetId, aArea, aPosition)
    *     Fired when a widget is added to an area. aWidgetId is the widget that
    *     was added, aArea the area it was added to, and aPosition the position
    *     in which it was added.
    *   - onWidgetMoved(aWidgetId, aArea, aOldPosition, aNewPosition)
    *     Fired when a widget is moved within its area. aWidgetId is the widget
    *     that was moved, aArea the area it was moved in, aOldPosition its old
    *     position, and aNewPosition its new position.
    *   - onWidgetRemoved(aWidgetId, aArea)
    *     Fired when a widget is removed from its area. aWidgetId is the widget
    *     that was removed, aArea the area it was removed from.
    *
    *   - onWidgetBeforeDOMChange(aNode, aNextNode, aContainer, aIsRemoval)
    *     Fired *before* a widget's DOM node is acted upon by CustomizableUI
    *     (to add, move or remove it). aNode is the DOM node changed, aNextNode
    *     the DOM node (if any) before which a widget will be inserted,
    *     aContainer the *actual* DOM container (could be an overflow panel in
    *     case of an overflowable toolbar), and aWasRemoval is true iff the
    *     action about to happen is the removal of the DOM node.
    *   - onWidgetAfterDOMChange(aNode, aNextNode, aContainer, aWasRemoval)
    *     Like onWidgetBeforeDOMChange, but fired after the change to the DOM
    *     node of the widget.
    *
    *   - onWidgetReset(aNode, aContainer)
    *     Fired after a reset to default placements moves a widget's node to a
    *     different location. aNode is the widget's node, aContainer is the
    *     area it was moved into (NB: it might already have been there and been
    *     moved to a different position!)
    *   - onWidgetUndoMove(aNode, aContainer)
    *     Fired after undoing a reset to default placements moves a widget's
    *     node to a different location. aNode is the widget's node, aContainer
    *     is the area it was moved into (NB: it might already have been there
    *     and been moved to a different position!)
    *   - onAreaReset(aArea, aContainer)
    *     Fired after a reset to default placements is complete on an area's
    *     DOM node. Note that this is fired for each DOM node. aArea is the area
    *     that was reset, aContainer the DOM node that was reset.
    *
    *   - onWidgetCreated(aWidgetId)
    *     Fired when a widget with id aWidgetId has been created, but before it
    *     is added to any placements or any DOM nodes have been constructed.
    *     Only fired for API-based widgets.
    *   - onWidgetAfterCreation(aWidgetId, aArea)
    *     Fired after a widget with id aWidgetId has been created, and has been
    *     added to either its default area or the area in which it was placed
    *     previously. If the widget has no default area and/or it has never
    *     been placed anywhere, aArea may be null. Only fired for API-based
    *     widgets.
    *   - onWidgetDestroyed(aWidgetId)
    *     Fired when widgets are destroyed. aWidgetId is the widget that is
    *     being destroyed. Only fired for API-based widgets.
    *   - onWidgetInstanceRemoved(aWidgetId, aDocument)
    *     Fired when a window is unloaded and a widget's instance is destroyed
    *     because of this. Only fired for API-based widgets.
    *
    *   - onWidgetDrag(aWidgetId, aArea)
    *     Fired both when and after customize mode drag handling system tries
    *     to determine the width and height of widget aWidgetId when dragged to a
    *     different area. aArea will be the area the item is dragged to, or
    *     undefined after the measurements have been done and the node has been
    *     moved back to its 'regular' area.
    *
    *   - onCustomizeStart(aWindow)
    *     Fired when opening customize mode in aWindow.
    *   - onCustomizeEnd(aWindow)
    *     Fired when exiting customize mode in aWindow.
    *
    *   - onWidgetOverflow(aNode, aContainer)
    *     Fired when a widget's DOM node is overflowing its container, a toolbar,
    *     and will be displayed in the overflow panel.
    *   - onWidgetUnderflow(aNode, aContainer)
    *     Fired when a widget's DOM node is *not* overflowing its container, a
    *     toolbar, anymore.
    *   - onWindowOpened(aWindow)
    *     Fired when a window has been opened that is managed by CustomizableUI,
    *     once all of the prerequisite setup has been done.
    *   - onWindowClosed(aWindow)
    *     Fired when a window that has been managed by CustomizableUI has been
    *     closed.
    *   - onAreaNodeRegistered(aArea, aContainer)
    *     Fired after an area node is first built when it is registered. This
    *     is often when the window has opened, but in the case of add-ons,
    *     could fire when the node has just been registered with CustomizableUI
    *     after an add-on update or disable/enable sequence.
    *   - onAreaNodeUnregistered(aArea, aContainer, aReason)
    *     Fired when an area node is explicitly unregistered by an API caller,
    *     or by a window closing. The aReason parameter indicates which of
    *     these is the case.
    */
   addListener: function(aListener) {
     CustomizableUIInternal.addListener(aListener);
   },
   /**
    * Remove a listener added with addListener
    * @param aListener the listener object to remove
    */
   removeListener: function(aListener) {
     CustomizableUIInternal.removeListener(aListener);
   },
   /**
    * Register a customizable area with CustomizableUI.
    * @param aName   the name of the area to register. Can only contain
    *                alphanumeric characters, dashes (-) and underscores (_).
    * @param aProps  the properties of the area. The following properties are
    *                recognized:
    *                - type:   the type of area. Either TYPE_TOOLBAR (default) or
    *                          TYPE_MENU_PANEL;
    *                - anchor: for a menu panel or overflowable toolbar, the
    *                          anchoring node for the panel.
    *                - legacy: set to true if you want customizableui to
    *                          automatically migrate the currentset attribute
    *                - overflowable: set to true if your toolbar is overflowable.
    *                                This requires an anchor, and only has an
    *                                effect for toolbars.
    *                - defaultPlacements: an array of widget IDs making up the
    *                                     default contents of the area
    *                - defaultCollapsed: (INTERNAL ONLY) applies if the type is TYPE_TOOLBAR, specifies
    *                                    if toolbar is collapsed by default (default to true).
    *                                    Specify null to ensure that reset/inDefaultArea don't care
    *                                    about a toolbar's collapsed state
    */
   registerArea: function(aName, aProperties) {
     CustomizableUIInternal.registerArea(aName, aProperties);
   },
   /**
    * Register a concrete node for a registered area. This method is automatically
    * called from any toolbar in the main browser window that has its
    * "customizable" attribute set to true. There should normally be no need to
    * call it yourself.
    *
    * Note that ideally, you should register your toolbar using registerArea
    * before any of the toolbars have their XBL bindings constructed (which
    * will happen when they're added to the DOM and are not hidden). If you
    * don't, and your toolbar has a defaultset attribute, CustomizableUI will
    * register it automatically. If your toolbar does not have a defaultset
    * attribute, the node will be saved for processing when you call
    * registerArea. Note that CustomizableUI won't restore state in the area,
    * allow the user to customize it in customize mode, or otherwise deal
    * with it, until the area has been registered.
    */
   registerToolbarNode: function(aToolbar, aExistingChildren) {
     CustomizableUIInternal.registerToolbarNode(aToolbar, aExistingChildren);
   },
   /**
    * Register the menu panel node. This method should not be called by anyone
    * apart from the built-in PanelUI.
    * @param aPanel the panel DOM node being registered.
    */
   registerMenuPanel: function(aPanel) {
     CustomizableUIInternal.registerMenuPanel(aPanel);
   },
   /**
    * Unregister a customizable area. The inverse of registerArea.
    *
    * Unregistering an area will remove all the (removable) widgets in the
    * area, which will return to the panel, and destroy all other traces
    * of the area within CustomizableUI. Note that this means the *contents*
    * of the area's DOM nodes will be moved to the panel or removed, but
    * the area's DOM nodes *themselves* will stay.
    *
    * Furthermore, by default the placements of the area will be kept in the
    * saved state (!) and restored if you re-register the area at a later
    * point. This is useful for e.g. add-ons that get disabled and then
    * re-enabled (e.g. when they update).
    *
    * You can override this last behaviour (and destroy the placements
    * information in the saved state) by passing true for aDestroyPlacements.
    *
    * @param aName              the name of the area to unregister
    * @param aDestroyPlacements whether to destroy the placements information
    *                           for the area, too.
    */
   unregisterArea: function(aName, aDestroyPlacements) {
     CustomizableUIInternal.unregisterArea(aName, aDestroyPlacements);
   },
   /**
    * Add a widget to an area.
    * If the area to which you try to add is not known to CustomizableUI,
    * this will throw.
    * If the area to which you try to add has not yet been restored from its
    * legacy state, this will postpone the addition.
    * If the area to which you try to add is the same as the area in which
    * the widget is currently placed, this will do the same as
    * moveWidgetWithinArea.
    * If the widget cannot be removed from its original location, this will
    * no-op.
    *
    * This will fire an onWidgetAdded notification,
    * and an onWidgetBeforeDOMChange and onWidgetAfterDOMChange notification
    * for each window CustomizableUI knows about.
    *
    * @param aWidgetId the ID of the widget to add
    * @param aArea     the ID of the area to add the widget to
    * @param aPosition the position at which to add the widget. If you do not
    *                  pass a position, the widget will be added to the end
    *                  of the area.
    */
   addWidgetToArea: function(aWidgetId, aArea, aPosition) {
     CustomizableUIInternal.addWidgetToArea(aWidgetId, aArea, aPosition);
   },
   /**
    * Remove a widget from its area. If the widget cannot be removed from its
    * area, or is not in any area, this will no-op. Otherwise, this will fire an
    * onWidgetRemoved notification, and an onWidgetBeforeDOMChange and
    * onWidgetAfterDOMChange notification for each window CustomizableUI knows
    * about.
    *
    * @param aWidgetId the ID of the widget to remove
    */
   removeWidgetFromArea: function(aWidgetId) {
     CustomizableUIInternal.removeWidgetFromArea(aWidgetId);
   },
   /**
    * Move a widget within an area.
    * If the widget is not in any area, this will no-op.
    * If the widget is already at the indicated position, this will no-op.
    *
    * Otherwise, this will move the widget and fire an onWidgetMoved notification,
    * and an onWidgetBeforeDOMChange and onWidgetAfterDOMChange notification for
    * each window CustomizableUI knows about.
    *
    * @param aWidgetId the ID of the widget to move
    * @param aPosition the position to move the widget to.
    *                  Negative values or values greater than the number of
    *                  widgets will be interpreted to mean moving the widget to
    *                  respectively the first or last position.
    */
   moveWidgetWithinArea: function(aWidgetId, aPosition) {
     CustomizableUIInternal.moveWidgetWithinArea(aWidgetId, aPosition);
   },
   /**
    * Ensure a XUL-based widget created in a window after areas were
    * initialized moves to its correct position.
    * This is roughly equivalent to manually looking up the position and using
    * insertItem in the old API, but a lot less work for consumers.
    * Always prefer this over using toolbar.insertItem (which might no-op
    * because it delegates to addWidgetToArea) or, worse, moving items in the
    * DOM yourself.
    *
    * @param aWidgetId the ID of the widget that was just created
    * @param aWindow the window in which you want to ensure it was added.
    *
    * NB: why is this API per-window, you wonder? Because if you need this,
    * presumably you yourself need to create the widget in all the windows
    * and need to loop through them anyway.
    */
   ensureWidgetPlacedInWindow: function(aWidgetId, aWindow) {
     return CustomizableUIInternal.ensureWidgetPlacedInWindow(aWidgetId, aWindow);
   },
   /**
    * Start a batch update of items.
    * During a batch update, the customization state is not saved to the user's
    * preferences file, in order to reduce (possibly sync) IO.
    * Calls to begin/endBatchUpdate may be nested.
    *
    * Callers should ensure that NO MATTER WHAT they call endBatchUpdate once
    * for each call to beginBatchUpdate, even if there are exceptions in the
    * code in the batch update. Otherwise, for the duration of the
    * Firefox session, customization state is never saved. Typically, you
    * would do this using a try...finally block.
    */
   beginBatchUpdate: function() {
     CustomizableUIInternal.beginBatchUpdate();
   },
   /**
    * End a batch update. See the documentation for beginBatchUpdate above.
    *
    * State is not saved if we believe it is identical to the last known
    * saved state. State is only ever saved when all batch updates have
    * finished (ie there has been 1 endBatchUpdate call for each
    * beginBatchUpdate call). If any of the endBatchUpdate calls pass
    * aForceDirty=true, we will flush to the prefs file.
    *
    * @param aForceDirty force CustomizableUI to flush to the prefs file when
    *                    all batch updates have finished.
    */
   endBatchUpdate: function(aForceDirty) {
     CustomizableUIInternal.endBatchUpdate(aForceDirty);
   },
   /**
    * Create a widget.
    *
    * To create a widget, you should pass an object with its desired
    * properties. The following properties are supported:
    *
    * - id:            the ID of the widget (required).
    * - type:          a string indicating the type of widget. Possible types
    *                  are:
    *                  'button' - for simple button widgets (the default)
    *                  'view'   - for buttons that open a panel or subview,
    *                             depending on where they are placed.
    *                  'custom' - for fine-grained control over the creation
    *                             of the widget.
    * - viewId:        Only useful for views (and required there): the id of the
    *                  <panelview> that should be shown when clicking the widget.
    * - onBuild(aDoc): Only useful for custom widgets (and required there); a
    *                  function that will be invoked with the document in which
    *                  to build a widget. Should return the DOM node that has
    *                  been constructed.
    * - onBeforeCreated(aDoc): Attached to all non-custom widgets; a function
    *                  that will be invoked before the widget gets a DOM node
    *                  constructed, passing the document in which that will happen.
    *                  This is useful especially for 'view' type widgets that need
    *                  to construct their views on the fly (e.g. from bootstrapped
    *                  add-ons)
    * - onCreated(aNode): Attached to all widgets; a function that will be invoked
    *                  whenever the widget has a DOM node constructed, passing the
    *                  constructed node as an argument.
    * - onCommand(aEvt): Only useful for button widgets; a function that will be
    *                    invoked when the user activates the button.
    * - onClick(aEvt): Attached to all widgets; a function that will be invoked
    *                  when the user clicks the widget.
    * - onViewShowing(aEvt): Only useful for views; a function that will be
    *                  invoked when a user shows your view.
    * - onViewHiding(aEvt): Only useful for views; a function that will be
    *                  invoked when a user hides your view.
    * - tooltiptext:   string to use for the tooltip of the widget
    * - label:         string to use for the label of the widget
    * - removable:     whether the widget is removable (optional, default: true)
    *                  NB: if you specify false here, you must provide a
    *                  defaultArea, too.
    * - overflows:     whether widget can overflow when in an overflowable
    *                  toolbar (optional, default: true)
    * - defaultArea:   default area to add the widget to
    *                  (optional, default: none; required if non-removable)
    * - shortcutId:    id of an element that has a shortcut for this widget
    *                  (optional, default: null). This is only used to display
    *                  the shortcut as part of the tooltip for builtin widgets
    *                  (which have strings inside
    *                  customizableWidgets.properties). If you're in an add-on,
    *                  you should not set this property.
    * - showInPrivateBrowsing: whether to show the widget in private browsing
    *                          mode (optional, default: true)
    *
    * @param aProperties the specifications for the widget.
    * @return a wrapper around the created widget (see getWidget)
    */
   createWidget: function(aProperties) {
     return CustomizableUIInternal.wrapWidget(
       CustomizableUIInternal.createWidget(aProperties)
     );
   },
   /**
    * Destroy a widget
    *
    * If the widget is part of the default placements in an area, this will
    * remove it from there. It will also remove any DOM instances. However,
    * it will keep the widget in the placements for whatever area it was
    * in at the time. You can remove it from there yourself by calling
    * CustomizableUI.removeWidgetFromArea(aWidgetId).
    *
    * @param aWidgetId the ID of the widget to destroy
    */
   destroyWidget: function(aWidgetId) {
     CustomizableUIInternal.destroyWidget(aWidgetId);
   },
   /**
    * Get a wrapper object with information about the widget.
    * The object provides the following properties
    * (all read-only unless otherwise indicated):
    *
    * - id:            the widget's ID;
    * - type:          the type of widget (button, view, custom). For
    *                  XUL-provided widgets, this is always 'custom';
    * - provider:      the provider type of the widget, id est one of
    *                  PROVIDER_API or PROVIDER_XUL;
    * - forWindow(w):  a method to obtain a single window wrapper for a widget,
    *                  in the window w passed as the only argument;
    * - instances:     an array of all instances (single window wrappers)
    *                  of the widget. This array is NOT live;
    * - areaType:      the type of the widget's current area
    * - isGroup:       true; will be false for wrappers around single widget nodes;
    * - source:        for API-provided widgets, whether they are built-in to
    *                  Firefox or add-on-provided;
    * - disabled:      for API-provided widgets, whether the widget is currently
    *                  disabled. NB: this property is writable, and will toggle
    *                  all the widgets' nodes' disabled states;
    * - label:         for API-provied widgets, the label of the widget;
    * - tooltiptext:   for API-provided widgets, the tooltip of the widget;
    * - showInPrivateBrowsing: for API-provided widgets, whether the widget is
    *                          visible in private browsing;
    *
    * Single window wrappers obtained through forWindow(someWindow) or from the
    * instances array have the following properties
    * (all read-only unless otherwise indicated):
    *
    * - id:            the widget's ID;
    * - type:          the type of widget (button, view, custom). For
    *                  XUL-provided widgets, this is always 'custom';
    * - provider:      the provider type of the widget, id est one of
    *                  PROVIDER_API or PROVIDER_XUL;
    * - node:          reference to the corresponding DOM node;
    * - anchor:        the anchor on which to anchor panels opened from this
    *                  node. This will point to the overflow chevron on
    *                  overflowable toolbars if and only if your widget node
    *                  is overflowed, to the anchor for the panel menu
    *                  if your widget is inside the panel menu, and to the
    *                  node itself in all other cases;
    * - overflowed:    boolean indicating whether the node is currently in the
    *                  overflow panel of the toolbar;
    * - isGroup:       false; will be true for the group widget;
    * - label:         for API-provided widgets, convenience getter for the
    *                  label attribute of the DOM node;
    * - tooltiptext:   for API-provided widgets, convenience getter for the
    *                  tooltiptext attribute of the DOM node;
    * - disabled:      for API-provided widgets, convenience getter *and setter*
    *                  for the disabled state of this single widget. Note that
    *                  you may prefer to use the group wrapper's getter/setter
    *                  instead.
    *
    * @param aWidgetId the ID of the widget whose information you need
    * @return a wrapper around the widget as described above, or null if the
    *         widget is known not to exist (anymore). NB: non-null return
    *         is no guarantee the widget exists because we cannot know in
    *         advance if a XUL widget exists or not.
    */
   getWidget: function(aWidgetId) {
     return CustomizableUIInternal.wrapWidget(aWidgetId);
   },
   /**
    * Get an array of widget wrappers (see getWidget) for all the widgets
    * which are currently not in any area (so which are in the palette).
    *
    * @param aWindowPalette the palette (and by extension, the window) in which
    *                       CustomizableUI should look. This matters because of
    *                       course XUL-provided widgets could be available in
    *                       some windows but not others, and likewise
    *                       API-provided widgets might not exist in a private
    *                       window (because of the showInPrivateBrowsing
    *                       property).
    *
    * @return an array of widget wrappers (see getWidget)
    */
   getUnusedWidgets: function(aWindowPalette) {
     return CustomizableUIInternal.getUnusedWidgets(aWindowPalette).map(
       CustomizableUIInternal.wrapWidget,
       CustomizableUIInternal
     );
   },
   /**
    * Get an array of all the widget IDs placed in an area. This is roughly
    * equivalent to fetching the currentset attribute and splitting by commas
    * in the legacy APIs. Modifying the array will not affect CustomizableUI.
    *
    * @param aArea the ID of the area whose placements you want to obtain.
    * @return an array containing the widget IDs that are in the area.
    *
    * NB: will throw if called too early (before placements have been fetched)
    *     or if the area is not currently known to CustomizableUI.
    */
   getWidgetIdsInArea: function(aArea) {
     if (!gAreas.has(aArea)) {
       throw new Error("Unknown customization area: " + aArea);
     }
     if (!gPlacements.has(aArea)) {
       throw new Error("Area not yet restored");
     }
     // We need to clone this, as we don't want to let consumers muck with placements
     return [...gPlacements.get(aArea)];
   },
   /**
    * Get an array of widget wrappers for all the widgets in an area. This is
    * the same as calling getWidgetIdsInArea and .map() ing the result through
    * CustomizableUI.getWidget. Careful: this means that if there are IDs in there
    * which don't have corresponding DOM nodes (like in the old-style currentset
    * attribute), there might be nulls in this array, or items for which
    * wrapper.forWindow(win) will return null.
    *
    * @param aArea the ID of the area whose widgets you want to obtain.
    * @return an array of widget wrappers and/or null values for the widget IDs
    *         placed in an area.
    *
    * NB: will throw if called too early (before placements have been fetched)
    *     or if the area is not currently known to CustomizableUI.
    */
   getWidgetsInArea: function(aArea) {
     return this.getWidgetIdsInArea(aArea).map(
       CustomizableUIInternal.wrapWidget,
       CustomizableUIInternal
     );
   },
   /**
    * Obtain an array of all the area IDs known to CustomizableUI.
    * This array is created for you, so is modifiable without CustomizableUI
    * being affected.
    */
   get areas() {
     return [area for ([area, props] of gAreas)];
   },
   /**
    * Check what kind of area (toolbar or menu panel) an area is. This is
    * useful if you have a widget that needs to behave differently depending
    * on its location. Note that widget wrappers have a convenience getter
    * property (areaType) for this purpose.
    *
    * @param aArea the ID of the area whose type you want to know
    * @return TYPE_TOOLBAR or TYPE_MENU_PANEL depending on the area, null if
    *         the area is unknown.
    */
   getAreaType: function(aArea) {
     let area = gAreas.get(aArea);
     return area ? area.get("type") : null;
   },
   /**
    * Check if a toolbar is collapsed by default.
    *
    * @param aArea the ID of the area whose default-collapsed state you want to know.
    * @return `true` or `false` depending on the area, null if the area is unknown,
    *         or its collapsed state cannot normally be controlled by the user
    */
   isToolbarDefaultCollapsed: function(aArea) {
     let area = gAreas.get(aArea);
     return area ? area.get("defaultCollapsed") : null;
   },
   /**
    * Obtain the DOM node that is the customize target for an area in a
    * specific window.
    *
    * Areas can have a customization target that does not correspond to the
    * node itself. In particular, toolbars that have a customizationtarget
    * attribute set will have their customization target set to that node.
    * This means widgets will end up in the customization target, not in the
    * DOM node with the ID that corresponds to the area ID. This is useful
    * because it lets you have fixed content in a toolbar (e.g. the panel
    * menu item in the navbar) and have all the customizable widgets use
    * the customization target.
    *
    * Using this API yourself is discouraged; you should generally not need
    * to be asking for the DOM container node used for a particular area.
    * In particular, if you're wanting to check it in relation to a widget's
    * node, your DOM node might not be a direct child of the customize target
    * in a window if, for instance, the window is in customization mode, or if
    * this is an overflowable toolbar and the widget has been overflowed.
    *
    * @param aArea   the ID of the area whose customize target you want to have
    * @param aWindow the window where you want to fetch the DOM node.
    * @return the customize target DOM node for aArea in aWindow
    */
   getCustomizeTargetForArea: function(aArea, aWindow) {
     return CustomizableUIInternal.getCustomizeTargetForArea(aArea, aWindow);
   },
   /**
    * Reset the customization state back to its default.
    *
    * This is the nuclear option. You should never call this except if the user
    * explicitly requests it. Firefox does this when the user clicks the
    * "Restore Defaults" button in customize mode.
    */
   reset: function() {
     CustomizableUIInternal.reset();
   },
   /**
    * Undo the previous reset, can only be called immediately after a reset.
    * @return a promise that will be resolved when the operation is complete.
    */
   undoReset: function() {
     CustomizableUIInternal.undoReset();
   },
   /**
    * Remove a custom toolbar added in a previous version of Firefox or using
    * an add-on. NB: only works on the customizable toolbars generated by
    * the toolbox itself. Intended for use from CustomizeMode, not by
    * other consumers.
    * @param aToolbarId the ID of the toolbar to remove
    */
   removeExtraToolbar: function(aToolbarId) {
     CustomizableUIInternal.removeExtraToolbar(aToolbarId);
   },
   /**
    * Can the last Restore Defaults operation be undone.
    *
    * @return A boolean stating whether an undo of the
    *         Restore Defaults can be performed.
    */
   get canUndoReset() {
     return gUIStateBeforeReset.uiCustomizationState != null ||
            gUIStateBeforeReset.drawInTitlebar != null;
   },
   /**
    * Get the placement of a widget. This is by far the best way to obtain
    * information about what the state of your widget is. The internals of
    * this call are cheap (no DOM necessary) and you will know where the user
    * has put your widget.
    *
    * @param aWidgetId the ID of the widget whose placement you want to know
    * @return
    *   {
    *     area: "somearea", // The ID of the area where the widget is placed
    *     position: 42 // the index in the placements array corresponding to
    *                  // your widget.
    *   }
    *
    *   OR
    *
    *   null // if the widget is not placed anywhere (ie in the palette)
    */
   getPlacementOfWidget: function(aWidgetId) {
     return CustomizableUIInternal.getPlacementOfWidget(aWidgetId, true);
   },
   /**
    * Check if a widget can be removed from the area it's in.
    *
    * Note that if you're wanting to move the widget somewhere, you should
    * generally be checking canWidgetMoveToArea, because that will return
    * true if the widget is already in the area where you want to move it (!).
    *
    * NB: oh, also, this method might lie if the widget in question is a
    *     XUL-provided widget and there are no windows open, because it
    *     can obviously not check anything in this case. It will return
    *     true. You will be able to move the widget elsewhere. However,
    *     once the user reopens a window, the widget will move back to its
    *     'proper' area automagically.
    *
    * @param aWidgetId a widget ID or DOM node to check
    * @return true if the widget can be removed from its area,
    *          false otherwise.
    */
   isWidgetRemovable: function(aWidgetId) {
     return CustomizableUIInternal.isWidgetRemovable(aWidgetId);
   },
   /**
    * Check if a widget can be moved to a particular area. Like
    * isWidgetRemovable but better, because it'll return true if the widget
    * is already in the right area.
    *
    * @param aWidgetId the widget ID or DOM node you want to move somewhere
    * @param aArea     the area ID you want to move it to.
    * @return true if this is possible, false if it is not. The same caveats as
    *              for isWidgetRemovable apply, however, if no windows are open.
    */
   canWidgetMoveToArea: function(aWidgetId, aArea) {
     return CustomizableUIInternal.canWidgetMoveToArea(aWidgetId, aArea);
   },
   /**
    * Whether we're in a default state. Note that non-removable non-default
    * widgets and non-existing widgets are not taken into account in determining
    * whether we're in the default state.
    *
    * NB: this is a property with a getter. The getter is NOT cheap, because
    * it does smart things with non-removable non-default items, non-existent
    * items, and so forth. Please don't call unless necessary.
    */
   get inDefaultState() {
     return CustomizableUIInternal.inDefaultState;
   },
   /**
    * Set a toolbar's visibility state in all windows.
    * @param aToolbarId    the toolbar whose visibility should be adjusted
    * @param aIsVisible    whether the toolbar should be visible
    */
   setToolbarVisibility: function(aToolbarId, aIsVisible) {
     CustomizableUIInternal.setToolbarVisibility(aToolbarId, aIsVisible);
   },
   /**
    * Get a localized property off a (widget?) object.
    *
    * NB: this is unlikely to be useful unless you're in Firefox code, because
    *     this code uses the builtin widget stringbundle, and can't be told
    *     to use add-on-provided strings. It's mainly here as convenience for
    *     custom builtin widgets that build their own DOM but use the same
    *     stringbundle as the other builtin widgets.
    *
    * @param aWidget     the object whose property we should use to fetch a
    *                    localizable string;
    * @param aProp       the property on the object to use for the fetching;
    * @param aFormatArgs (optional) any extra arguments to use for a formatted
    *                    string;
    * @param aDef        (optional) the default to return if we don't find the
    *                    string in the stringbundle;
    *
    * @return the localized string, or aDef if the string isn't in the bundle.
    *         If no default is provided,
    *           if aProp exists on aWidget, we'll return that,
    *           otherwise we'll return the empty string
    *
    */
   getLocalizedProperty: function(aWidget, aProp, aFormatArgs, aDef) {
     return CustomizableUIInternal.getLocalizedProperty(aWidget, aProp,
       aFormatArgs, aDef);
   },
   /**
    * Given a node, walk up to the first panel in its ancestor chain, and
    * close it.
    *
    * @param aNode a node whose panel should be closed;
    */
   hidePanelForNode: function(aNode) {
     CustomizableUIInternal.hidePanelForNode(aNode);
   },
   /**
    * Check if a widget is a "special" widget: a spring, spacer or separator.
    *
    * @param aWidgetId the widget ID to check.
    * @return true if the widget is 'special', false otherwise.
    */
   isSpecialWidget: function(aWidgetId) {
     return CustomizableUIInternal.isSpecialWidget(aWidgetId);
   },
   /**
    * Add listeners to a panel that will close it. For use from the menu panel
    * and overflowable toolbar implementations, unlikely to be useful for
    * consumers.
    *
    * @param aPanel the panel to which listeners should be attached.
    */
   addPanelCloseListeners: function(aPanel) {
     CustomizableUIInternal.addPanelCloseListeners(aPanel);
   },
   /**
    * Remove close listeners that have been added to a panel with
    * addPanelCloseListeners. For use from the menu panel and overflowable
    * toolbar implementations, unlikely to be useful for consumers.
    *
    * @param aPanel the panel from which listeners should be removed.
    */
   removePanelCloseListeners: function(aPanel) {
     CustomizableUIInternal.removePanelCloseListeners(aPanel);
   },
   /**
    * Notify listeners a widget is about to be dragged to an area. For use from
    * Customize Mode only, do not use otherwise.
    *
    * @param aWidgetId the ID of the widget that is being dragged to an area.
    * @param aArea     the ID of the area to which the widget is being dragged.
    */
   onWidgetDrag: function(aWidgetId, aArea) {
     CustomizableUIInternal.notifyListeners("onWidgetDrag", aWidgetId, aArea);
   },
   /**
    * Notify listeners that a window is entering customize mode. For use from
    * Customize Mode only, do not use otherwise.
    * @param aWindow the window entering customize mode
    */
   notifyStartCustomizing: function(aWindow) {
     CustomizableUIInternal.notifyListeners("onCustomizeStart", aWindow);
   },
   /**
    * Notify listeners that a window is exiting customize mode. For use from
    * Customize Mode only, do not use otherwise.
    * @param aWindow the window exiting customize mode
    */
   notifyEndCustomizing: function(aWindow) {
     CustomizableUIInternal.notifyListeners("onCustomizeEnd", aWindow);
   },
   /**
    * Notify toolbox(es) of a particular event. If you don't pass aWindow,
    * all toolboxes will be notified. For use from Customize Mode only,
    * do not use otherwise.
    * @param aEvent the name of the event to send.
    * @param aDetails optional, the details of the event.
    * @param aWindow optional, the window in which to send the event.
    */
   dispatchToolboxEvent: function(aEvent, aDetails={}, aWindow=null) {
     CustomizableUIInternal.dispatchToolboxEvent(aEvent, aDetails, aWindow);
   },
   /**
    * Check whether an area is overflowable.
    *
    * @param aAreaId the ID of an area to check for overflowable-ness
    * @return true if the area is overflowable, false otherwise.
    */
   isAreaOverflowable: function(aAreaId) {
     let area = gAreas.get(aAreaId);
     return area ? area.get("type") == this.TYPE_TOOLBAR && area.get("overflowable")
                 : false;
   },
   /**
    * Obtain a string indicating the place of an element. This is intended
    * for use from customize mode; You should generally use getPlacementOfWidget
    * instead, which is cheaper because it does not use the DOM.
    *
    * @param aElement the DOM node whose place we need to check
    * @return "toolbar" if the node is in a toolbar, "panel" if it is in the
    *         menu panel, "palette" if it is in the (visible!) customization
    *         palette, undefined otherwise.
    */
   getPlaceForItem: function(aElement) {
     let place;
     let node = aElement;
     while (node && !place) {
       if (node.localName == "toolbar")
         place = "toolbar";
       else if (node.id == CustomizableUI.AREA_PANEL)
         place = "panel";
       else if (node.id == "customization-palette")
         place = "palette";
       node = node.parentNode;
     }
     return place;
   },
   /**
    * Check if a toolbar is builtin or not.
    * @param aToolbarId the ID of the toolbar you want to check
    */
   isBuiltinToolbar: function(aToolbarId) {
     return CustomizableUIInternal._builtinToolbars.has(aToolbarId);
   },
 };
 Object.freeze(this.CustomizableUI);
 Object.freeze(this.CustomizableUI.windows);
 /**
  * All external consumers of widgets are really interacting with these wrappers
  * which provide a common interface.
  */
 /**
  * WidgetGroupWrapper is the common interface for interacting with an entire
  * widget group - AKA, all instances of a widget across a series of windows.
  * This particular wrapper is only used for widgets created via the provider
  * API.
  */
 function WidgetGroupWrapper(aWidget) {
   this.isGroup = true;
   const kBareProps = ["id", "source", "type", "disabled", "label", "tooltiptext",
                       "showInPrivateBrowsing"];
   for (let prop of kBareProps) {
     let propertyName = prop;
     this.__defineGetter__(propertyName, function() aWidget[propertyName]);
   }
   this.__defineGetter__("provider", function() CustomizableUI.PROVIDER_API);
   this.__defineSetter__("disabled", function(aValue) {
     aValue = !!aValue;
     aWidget.disabled = aValue;
     for (let [,instance] of aWidget.instances) {
       instance.disabled = aValue;
     }
   });
   this.forWindow = function WidgetGroupWrapper_forWindow(aWindow) {
     let wrapperMap;
     if (!gSingleWrapperCache.has(aWindow)) {
       wrapperMap = new Map();
       gSingleWrapperCache.set(aWindow, wrapperMap);
     } else {
       wrapperMap = gSingleWrapperCache.get(aWindow);
     }
     if (wrapperMap.has(aWidget.id)) {
       return wrapperMap.get(aWidget.id);
     }
     let instance = aWidget.instances.get(aWindow.document);
     if (!instance &&
         (aWidget.showInPrivateBrowsing || !PrivateBrowsingUtils.isWindowPrivate(aWindow))) {
       instance = CustomizableUIInternal.buildWidget(aWindow.document,
                                                     aWidget);
     }
     let wrapper = new WidgetSingleWrapper(aWidget, instance);
     wrapperMap.set(aWidget.id, wrapper);
     return wrapper;
   };
   this.__defineGetter__("instances", function() {
     // Can't use gBuildWindows here because some areas load lazily:
     let placement = CustomizableUIInternal.getPlacementOfWidget(aWidget.id);
     if (!placement) {
       return [];
     }
     let area = placement.area;
     let buildAreas = gBuildAreas.get(area);
     if (!buildAreas) {
       return [];
     }
     return [this.forWindow(node.ownerDocument.defaultView) for (node of buildAreas)];
   });
   this.__defineGetter__("areaType", function() {
     let areaProps = gAreas.get(aWidget.currentArea);
     return areaProps && areaProps.get("type");
   });
   Object.freeze(this);
 }
 /**
  * A WidgetSingleWrapper is a wrapper around a single instance of a widget in
  * a particular window.
  */
 function WidgetSingleWrapper(aWidget, aNode) {
   this.isGroup = false;
   this.node = aNode;
   this.provider = CustomizableUI.PROVIDER_API;
   const kGlobalProps = ["id", "type"];
   for (let prop of kGlobalProps) {
     this[prop] = aWidget[prop];
   }
   const kNodeProps = ["label", "tooltiptext"];
   for (let prop of kNodeProps) {
     let propertyName = prop;
     // Look at the node for these, instead of the widget data, to ensure the
     // wrapper always reflects this live instance.
     this.__defineGetter__(propertyName,
                           function() aNode.getAttribute(propertyName));
   }
   this.__defineGetter__("disabled", function() aNode.disabled);
   this.__defineSetter__("disabled", function(aValue) {
     aNode.disabled = !!aValue;
   });
   this.__defineGetter__("anchor", function() {
     let anchorId;
     // First check for an anchor for the area:
     let placement = CustomizableUIInternal.getPlacementOfWidget(aWidget.id);
     if (placement) {
       anchorId = gAreas.get(placement.area).get("anchor");
     }
     if (!anchorId) {
       anchorId = aNode.getAttribute("cui-anchorid");
     }
     return anchorId ? aNode.ownerDocument.getElementById(anchorId)
                     : aNode;
   });
   this.__defineGetter__("overflowed", function() {
     return aNode.getAttribute("overflowedItem") == "true";
   });
   Object.freeze(this);
 }
 /**
  * XULWidgetGroupWrapper is the common interface for interacting with an entire
  * widget group - AKA, all instances of a widget across a series of windows.
  * This particular wrapper is only used for widgets created via the old-school
  * XUL method (overlays, or programmatically injecting toolbaritems, or other
  * such things).
  */
 //XXXunf Going to need to hook this up to some events to keep it all live.
 function XULWidgetGroupWrapper(aWidgetId) {
   this.isGroup = true;
   this.id = aWidgetId;
   this.type = "custom";
   this.provider = CustomizableUI.PROVIDER_XUL;
   this.forWindow = function XULWidgetGroupWrapper_forWindow(aWindow) {
     let wrapperMap;
     if (!gSingleWrapperCache.has(aWindow)) {
       wrapperMap = new Map();
       gSingleWrapperCache.set(aWindow, wrapperMap);
     } else {
       wrapperMap = gSingleWrapperCache.get(aWindow);
     }
     if (wrapperMap.has(aWidgetId)) {
       return wrapperMap.get(aWidgetId);
     }
     let instance = aWindow.document.getElementById(aWidgetId);
     if (!instance) {
       // Toolbar palettes aren't part of the document, so elements in there
       // won't be found via document.getElementById().
       instance = aWindow.gNavToolbox.palette.getElementsByAttribute("id", aWidgetId)[0];
     }
     let wrapper = new XULWidgetSingleWrapper(aWidgetId, instance, aWindow.document);
     wrapperMap.set(aWidgetId, wrapper);
     return wrapper;
   };
   this.__defineGetter__("areaType", function() {
     let placement = CustomizableUIInternal.getPlacementOfWidget(aWidgetId);
     if (!placement) {
       return null;
     }
     let areaProps = gAreas.get(placement.area);
     return areaProps && areaProps.get("type");
   });
   this.__defineGetter__("instances", function() {
     return [this.forWindow(win) for ([win,] of gBuildWindows)];
   });
   Object.freeze(this);
 }
 /**
  * A XULWidgetSingleWrapper is a wrapper around a single instance of a XUL
  * widget in a particular window.
  */
 function XULWidgetSingleWrapper(aWidgetId, aNode, aDocument) {
   this.isGroup = false;
   this.id = aWidgetId;
   this.type = "custom";
   this.provider = CustomizableUI.PROVIDER_XUL;
   let weakDoc = Cu.getWeakReference(aDocument);
   // If we keep a strong ref, the weak ref will never die, so null it out:
   aDocument = null;
   this.__defineGetter__("node", function() {
     // If we've set this to null (further down), we're sure there's nothing to
     // be gotten here, so bail out early:
     if (!weakDoc) {
       return null;
     }
     if (aNode) {
       // Return the last known node if it's still in the DOM...
       if (aNode.ownerDocument.contains(aNode)) {
         return aNode;
       }
       // ... or the toolbox
       let toolbox = aNode.ownerDocument.defaultView.gNavToolbox;
       if (toolbox && toolbox.palette && aNode.parentNode == toolbox.palette) {
         return aNode;
       }
       // If it isn't, clear the cached value and fall through to the "slow" case:
       aNode = null;
     }
     let doc = weakDoc.get();
     if (doc) {
       // Store locally so we can cache the result:
       aNode = CustomizableUIInternal.findWidgetInWindow(aWidgetId, doc.defaultView);
       return aNode;
     }
     // The weakref to the document is dead, we're done here forever more:
     weakDoc = null;
     return null;
   });
   this.__defineGetter__("anchor", function() {
     let anchorId;
     // First check for an anchor for the area:
     let placement = CustomizableUIInternal.getPlacementOfWidget(aWidgetId);
     if (placement) {
       anchorId = gAreas.get(placement.area).get("anchor");
     }
     let node = this.node;
     if (!anchorId && node) {
       anchorId = node.getAttribute("cui-anchorid");
     }
     return (anchorId && node) ? node.ownerDocument.getElementById(anchorId) : node;
   });
   this.__defineGetter__("overflowed", function() {
     let node = this.node;
     if (!node) {
       return false;
     }
     return node.getAttribute("overflowedItem") == "true";
   });
   Object.freeze(this);
 }
 const LAZY_RESIZE_INTERVAL_MS = 200;
 function OverflowableToolbar(aToolbarNode) {
   this._toolbar = aToolbarNode;
   this._collapsed = new Map();
   this._enabled = true;
   this._toolbar.setAttribute("overflowable", "true");
   let doc = this._toolbar.ownerDocument;
   this._target = this._toolbar.customizationTarget;
   this._list = doc.getElementById(this._toolbar.getAttribute("overflowtarget"));
   this._list.toolbox = this._toolbar.toolbox;
   this._list.customizationTarget = this._list;
   let window = this._toolbar.ownerDocument.defaultView;
   if (window.gBrowserInit.delayedStartupFinished) {
     this.init();
   } else {
     Services.obs.addObserver(this, "browser-delayed-startup-finished", false);
   }
 }
 OverflowableToolbar.prototype = {
   initialized: false,
   _forceOnOverflow: false,
   observe: function(aSubject, aTopic, aData) {
     if (aTopic == "browser-delayed-startup-finished" &&
         aSubject == this._toolbar.ownerDocument.defaultView) {
       Services.obs.removeObserver(this, "browser-delayed-startup-finished");
       this.init();
     }
   },
   init: function() {
     let doc = this._toolbar.ownerDocument;
     let window = doc.defaultView;
     window.addEventListener("resize", this);
     window.gNavToolbox.addEventListener("customizationstarting", this);
     window.gNavToolbox.addEventListener("aftercustomization", this);
     let chevronId = this._toolbar.getAttribute("overflowbutton");
     this._chevron = doc.getElementById(chevronId);
     this._chevron.addEventListener("command", this);
     let panelId = this._toolbar.getAttribute("overflowpanel");
     this._panel = doc.getElementById(panelId);
     this._panel.addEventListener("popuphiding", this);
     CustomizableUIInternal.addPanelCloseListeners(this._panel);
     CustomizableUI.addListener(this);
     // The 'overflow' event may have been fired before init was called.
     if (this._toolbar.overflowedDuringConstruction) {
       this.onOverflow(this._toolbar.overflowedDuringConstruction);
       this._toolbar.overflowedDuringConstruction = null;
     }
     this.initialized = true;
   },
   uninit: function() {
     this._toolbar.removeEventListener("overflow", this._toolbar);
     this._toolbar.removeEventListener("underflow", this._toolbar);
     this._toolbar.removeAttribute("overflowable");
     if (!this.initialized) {
       Services.obs.removeObserver(this, "browser-delayed-startup-finished");
       return;
     }
     this._disable();
     let window = this._toolbar.ownerDocument.defaultView;
     window.removeEventListener("resize", this);
     window.gNavToolbox.removeEventListener("customizationstarting", this);
     window.gNavToolbox.removeEventListener("aftercustomization", this);
     this._chevron.removeEventListener("command", this);
     this._panel.removeEventListener("popuphiding", this);
     CustomizableUI.removeListener(this);
     CustomizableUIInternal.removePanelCloseListeners(this._panel);
   },
   handleEvent: function(aEvent) {
     switch(aEvent.type) {
       case "resize":
         this._onResize(aEvent);
         break;
       case "command":
         if (aEvent.target == this._chevron) {
           this._onClickChevron(aEvent);
         } else {
           this._panel.hidePopup();
         }
         break;
       case "popuphiding":
         this._onPanelHiding(aEvent);
         break;
       case "customizationstarting":
         this._disable();
         break;
       case "aftercustomization":
         this._enable();
         break;
     }
   },
   show: function() {
     let deferred = Promise.defer();
     if (this._panel.state == "open") {
       deferred.resolve();
       return deferred.promise;
     }
     let doc = this._panel.ownerDocument;
     this._panel.hidden = false;
     let contextMenu = doc.getElementById(this._panel.getAttribute("context"));
     gELS.addSystemEventListener(contextMenu, 'command', this, true);
     let anchor = doc.getAnonymousElementByAttribute(this._chevron, "class", "toolbarbutton-icon");
     this._panel.openPopup(anchor || this._chevron);
     this._chevron.open = true;
     this._panel.addEventListener("popupshown", function onPopupShown() {
       this.removeEventListener("popupshown", onPopupShown);
       deferred.resolve();
     });
     return deferred.promise;
   },
   _onClickChevron: function(aEvent) {
     if (this._chevron.open) {
       this._panel.hidePopup();
       this._chevron.open = false;
     } else {
       this.show();
     }
   },
   _onPanelHiding: function(aEvent) {
     this._chevron.open = false;
     let doc = aEvent.target.ownerDocument;
     let contextMenu = doc.getElementById(this._panel.getAttribute("context"));
     gELS.removeSystemEventListener(contextMenu, 'command', this, true);
   },
   onOverflow: function(aEvent) {
     if (!this._enabled ||
         (aEvent && aEvent.target != this._toolbar.customizationTarget))
       return;
     let child = this._target.lastChild;
     while (child && this._target.scrollLeftMax > 0) {
       let prevChild = child.previousSibling;
       if (child.getAttribute("overflows") != "false") {
         this._collapsed.set(child.id, this._target.clientWidth);
         child.setAttribute("overflowedItem", true);
         child.setAttribute("cui-anchorid", this._chevron.id);
         CustomizableUIInternal.notifyListeners("onWidgetOverflow", child, this._target);
         this._list.insertBefore(child, this._list.firstChild);
         if (!this._toolbar.hasAttribute("overflowing")) {
           CustomizableUI.addListener(this);
         }
         this._toolbar.setAttribute("overflowing", "true");
       }
       child = prevChild;
     };
     let win = this._target.ownerDocument.defaultView;
     win.UpdateUrlbarSearchSplitterState();
   },
   _onResize: function(aEvent) {
     if (!this._lazyResizeHandler) {
       this._lazyResizeHandler = new DeferredTask(this._onLazyResize.bind(this),
                                                  LAZY_RESIZE_INTERVAL_MS);
     }
     this._lazyResizeHandler.arm();
   },
   _moveItemsBackToTheirOrigin: function(shouldMoveAllItems) {
     let placements = gPlacements.get(this._toolbar.id);
     while (this._list.firstChild) {
       let child = this._list.firstChild;
       let minSize = this._collapsed.get(child.id);
       if (!shouldMoveAllItems &&
           minSize &&
           this._target.clientWidth <= minSize) {
         return;
       }
       this._collapsed.delete(child.id);
       let beforeNodeIndex = placements.indexOf(child.id) + 1;
       // If this is a skipintoolbarset item, meaning it doesn't occur in the placements list,
       // we're inserting it at the end. This will mean first-in, first-out (more or less)
       // leading to as little change in order as possible.
       if (beforeNodeIndex == 0) {
         beforeNodeIndex = placements.length;
       }
       let inserted = false;
       for (; beforeNodeIndex < placements.length; beforeNodeIndex++) {
         let beforeNode = this._target.getElementsByAttribute("id", placements[beforeNodeIndex])[0];
         if (beforeNode) {
           this._target.insertBefore(child, beforeNode);
           inserted = true;
           break;
         }
       }
       if (!inserted) {
         this._target.appendChild(child);
       }
       child.removeAttribute("cui-anchorid");
       child.removeAttribute("overflowedItem");
       CustomizableUIInternal.notifyListeners("onWidgetUnderflow", child, this._target);
     }
     let win = this._target.ownerDocument.defaultView;
     win.UpdateUrlbarSearchSplitterState();
     if (!this._collapsed.size) {
       this._toolbar.removeAttribute("overflowing");
       CustomizableUI.removeListener(this);
     }
   },
   _onLazyResize: function() {
     if (!this._enabled)
       return;
     if (this._target.scrollLeftMax > 0) {
       this.onOverflow();
     } else {
       this._moveItemsBackToTheirOrigin();
     }
   },
   _disable: function() {
     this._enabled = false;
     this._moveItemsBackToTheirOrigin(true);
     if (this._lazyResizeHandler) {
       this._lazyResizeHandler.disarm();
     }
   },
   _enable: function() {
     this._enabled = true;
     this.onOverflow();
   },
   onWidgetBeforeDOMChange: function(aNode, aNextNode, aContainer) {
     if (aContainer != this._target && aContainer != this._list) {
       return;
     }
     // When we (re)move an item, update all the items that come after it in the list
     // with the minsize *of the item before the to-be-removed node*. This way, we
     // ensure that we try to move items back as soon as that's possible.
     if (aNode.parentNode == this._list) {
       let updatedMinSize;
       if (aNode.previousSibling) {
         updatedMinSize = this._collapsed.get(aNode.previousSibling.id);
       } else {
         // Force (these) items to try to flow back into the bar:
         updatedMinSize = 1;
       }
       let nextItem = aNode.nextSibling;
       while (nextItem) {
         this._collapsed.set(nextItem.id, updatedMinSize);
         nextItem = nextItem.nextSibling;
       }
     }
   },
   onWidgetAfterDOMChange: function(aNode, aNextNode, aContainer) {
     if (aContainer != this._target && aContainer != this._list) {
       return;
     }
     let nowInBar = aNode.parentNode == aContainer;
     let nowOverflowed = aNode.parentNode == this._list;
     let wasOverflowed = this._collapsed.has(aNode.id);
     // If this wasn't overflowed before...
     if (!wasOverflowed) {
       // ... but it is now, then we added to the overflow panel. Exciting stuff:
       if (nowOverflowed) {
         // NB: we're guaranteed that it has a previousSibling, because if it didn't,
         // we would have added it to the toolbar instead. See getOverflowedNextNode.
         let prevId = aNode.previousSibling.id;
         let minSize = this._collapsed.get(prevId);
         this._collapsed.set(aNode.id, minSize);
         aNode.setAttribute("cui-anchorid", this._chevron.id);
         aNode.setAttribute("overflowedItem", true);
         CustomizableUIInternal.notifyListeners("onWidgetOverflow", aNode, this._target);
       }
       // If it is not overflowed and not in the toolbar, and was not overflowed
       // either, it moved out of the toolbar. That means there's now space in there!
       // Let's try to move stuff back:
       else if (!nowInBar) {
         this._moveItemsBackToTheirOrigin(true);
       }
       // If it's in the toolbar now, then we don't care. An overflow event may
       // fire afterwards; that's ok!
     }
     // If it used to be overflowed...
     else {
       // ... and isn't anymore, let's remove our bookkeeping:
       if (!nowOverflowed) {
         this._collapsed.delete(aNode.id);
         aNode.removeAttribute("cui-anchorid");
         aNode.removeAttribute("overflowedItem");
         CustomizableUIInternal.notifyListeners("onWidgetUnderflow", aNode, this._target);
         if (!this._collapsed.size) {
           this._toolbar.removeAttribute("overflowing");
           CustomizableUI.removeListener(this);
         }
       }
       // but if it still is, it must have changed places. Bookkeep:
       else {
         if (aNode.previousSibling) {
           let prevId = aNode.previousSibling.id;
           let minSize = this._collapsed.get(prevId);
           this._collapsed.set(aNode.id, minSize);
         } else {
           // If it's now the first item in the overflow list,
           // maybe we can return it:
           this._moveItemsBackToTheirOrigin();
         }
       }
     }
   },
   findOverflowedInsertionPoints: function(aNode) {
     let newNodeCanOverflow = aNode.getAttribute("overflows") != "false";
     let areaId = this._toolbar.id;
     let placements = gPlacements.get(areaId);
     let nodeIndex = placements.indexOf(aNode.id);
     let nodeBeforeNewNodeIsOverflown = false;
     let loopIndex = -1;
     while (++loopIndex < placements.length) {
       let nextNodeId = placements[loopIndex];
       if (loopIndex > nodeIndex) {
         if (newNodeCanOverflow && this._collapsed.has(nextNodeId)) {
           let nextNode = this._list.getElementsByAttribute("id", nextNodeId).item(0);
           if (nextNode) {
             return [this._list, nextNode];
           }
         }
         if (!nodeBeforeNewNodeIsOverflown || !newNodeCanOverflow) {
           let nextNode = this._target.getElementsByAttribute("id", nextNodeId).item(0);
           if (nextNode) {
             return [this._target, nextNode];
           }
         }
       } else if (loopIndex < nodeIndex && this._collapsed.has(nextNodeId)) {
         nodeBeforeNewNodeIsOverflown = true;
       }
     }
     let containerForAppending = (this._collapsed.size && newNodeCanOverflow) ?
                                 this._list : this._target;
     return [containerForAppending, null];
   },
   getContainerFor: function(aNode) {
     if (aNode.getAttribute("overflowedItem") == "true") {
       return this._list;
     }
     return this._target;
   },
 };
 CustomizableUIInternal.initialize();

The Tor Browser / annotate

browser/components/customizableui/src/CustomizableUI.jsm@8bccb770b82d (annotated)

browser/components/customizableui/src/CustomizableUI.jsm