The Tor Browser: browser/components/tabview/ui.js@6474c204b198 (annotated)

browser/components/tabview/ui.js@6474c204b198 (annotated)

browser/components/tabview/ui.js

Wed, 31 Dec 2014 06:09:35 +0100

author: Michael Schloh von Bennewitz <michael@schloh.com>
date: Wed, 31 Dec 2014 06:09:35 +0100
changeset 0: 6474c204b198
permissions: -rw-r--r--

Cloned upstream origin tor-browser at tor-browser-31.3.0esr-4.5-1-build1
revision ID fc1c9ff7c1b2defdbc039f12214767608f46423f for hacking purpose.

 /* 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/. */
 // **********
 // Title: ui.js
 let Keys = { meta: false };
 // ##########
 // Class: UI
 // Singleton top-level UI manager.
 let UI = {
   // Variable: _frameInitialized
   // True if the Tab View UI frame has been initialized.
   _frameInitialized: false,
   // Variable: _pageBounds
   // Stores the page bounds.
   _pageBounds: null,
   // Variable: _closedLastVisibleTab
   // If true, the last visible tab has just been closed in the tab strip.
   _closedLastVisibleTab: false,
   // Variable: _closedSelectedTabInTabView
   // If true, a select tab has just been closed in TabView.
   _closedSelectedTabInTabView: false,
   // Variable: restoredClosedTab
   // If true, a closed tab has just been restored.
   restoredClosedTab: false,
   // Variable: _isChangingVisibility
   // Tracks whether we're currently in the process of showing/hiding the tabview.
   _isChangingVisibility: false,
   // Variable: _reorderTabItemsOnShow
   // Keeps track of the <GroupItem>s which their tab items' tabs have been moved
   // and re-orders the tab items when switching to TabView.
   _reorderTabItemsOnShow: [],
   // Variable: _reorderTabsOnHide
   // Keeps track of the <GroupItem>s which their tab items have been moved in
   // TabView UI and re-orders the tabs when switcing back to main browser.
   _reorderTabsOnHide: [],
   // Variable: _currentTab
   // Keeps track of which xul:tab we are currently on.
   // Used to facilitate zooming down from a previous tab.
   _currentTab: null,
   // Variable: _eventListeners
   // Keeps track of event listeners added to the AllTabs object.
   _eventListeners: {},
   // Variable: _cleanupFunctions
   // An array of functions to be called at uninit time
   _cleanupFunctions: [],
   // Constant: _maxInteractiveWait
   // If the UI is in the middle of an operation, this is the max amount of
   // milliseconds to wait between input events before we no longer consider
   // the operation interactive.
   _maxInteractiveWait: 250,
   // Variable: _storageBusy
   // Tells whether the storage is currently busy or not.
   _storageBusy: false,
   // Variable: isDOMWindowClosing
   // Tells wether the parent window is about to close
   isDOMWindowClosing: false,
   // Variable: _browserKeys
   // Used to keep track of allowed browser keys.
   _browserKeys: null,
   // Variable: _browserKeysWithShift
   // Used to keep track of allowed browser keys with Shift key combination.
   _browserKeysWithShift: null,
   // Variable: ignoreKeypressForSearch
   // Used to prevent keypress being handled after quitting search mode.
   ignoreKeypressForSearch: false,
   // Variable: _lastOpenedTab
   // Used to keep track of the last opened tab.
   _lastOpenedTab: null,
   // Variable: _originalSmoothScroll
   // Used to keep track of the tab strip smooth scroll value.
   _originalSmoothScroll: null,
   // ----------
   // Function: toString
   // Prints [UI] for debug use
   toString: function UI_toString() {
     return "[UI]";
   },
   // ----------
   // Function: init
   // Must be called after the object is created.
   init: function UI_init() {
     try {
       let self = this;
       // initialize the direction of the page
       this._initPageDirection();
       // ___ storage
       Storage.init();
       if (Storage.readWindowBusyState(gWindow))
         this.storageBusy();
       let data = Storage.readUIData(gWindow);
       this._storageSanity(data);
       this._pageBounds = data.pageBounds;
       // ___ search
       Search.init();
       Telemetry.init();
       // ___ currentTab
       this._currentTab = gBrowser.selectedTab;
       // ___ exit button
       iQ("#exit-button").click(function() {
         self.exit();
         self.blurAll();
       })
       .attr("title", tabviewString("button.exitTabGroups"));
       // When you click on the background/empty part of TabView,
       // we create a new groupItem.
       iQ(gTabViewFrame.contentDocument).mousedown(function(e) {
         if (iQ(":focus").length > 0) {
           iQ(":focus").each(function(element) {
             // don't fire blur event if the same input element is clicked.
             if (e.target != element && element.nodeName == "INPUT")
               element.blur();
           });
         }
         if (e.originalTarget.id == "content" &&
             Utils.isLeftClick(e) &&
             e.detail == 1) {
           self._createGroupItemOnDrag(e);
         }
       });
       iQ(gTabViewFrame.contentDocument).dblclick(function(e) {
         if (e.originalTarget.id != "content")
           return;
         // Create a group with one tab on double click
         let box =
           new Rect(e.clientX - Math.floor(TabItems.tabWidth/2),
                    e.clientY - Math.floor(TabItems.tabHeight/2),
                    TabItems.tabWidth, TabItems.tabHeight);
         box.inset(-30, -30);
         let opts = {immediately: true, bounds: box};
         let groupItem = new GroupItem([], opts);
         groupItem.newTab();
         gTabView.firstUseExperienced = true;
       });
       iQ(window).bind("unload", function() {
         self.uninit();
       });
       // ___ setup DOMWillOpenModalDialog message handler
       let mm = gWindow.messageManager;
       let callback = this._onDOMWillOpenModalDialog.bind(this);
       mm.addMessageListener("Panorama:DOMWillOpenModalDialog", callback);
       this._cleanupFunctions.push(function () {
         mm.removeMessageListener("Panorama:DOMWillOpenModalDialog", callback);
       });
       // ___ setup key handlers
       this._setTabViewFrameKeyHandlers();
       // ___ add tab action handlers
       this._addTabActionHandlers();
       // ___ groups
       GroupItems.init();
       GroupItems.pauseArrange();
       let hasGroupItemsData = GroupItems.load();
       // ___ tabs
       TabItems.init();
       TabItems.pausePainting();
       // ___ favicons
       FavIcons.init();
       if (!hasGroupItemsData)
         this.reset();
       // ___ resizing
       if (this._pageBounds)
         this._resize(true);
       else
         this._pageBounds = Items.getPageBounds();
       iQ(window).resize(function() {
         self._resize();
       });
       // ___ setup event listener to save canvas images
       let onWindowClosing = function () {
         gWindow.removeEventListener("SSWindowClosing", onWindowClosing, false);
         // XXX bug #635975 - don't unlink the tab if the dom window is closing.
         self.isDOMWindowClosing = true;
         if (self.isTabViewVisible())
           GroupItems.removeHiddenGroups();
         TabItems.saveAll();
         self._save();
       };
       gWindow.addEventListener("SSWindowClosing", onWindowClosing);
       this._cleanupFunctions.push(function () {
         gWindow.removeEventListener("SSWindowClosing", onWindowClosing);
       });
       // ___ load frame script
       let frameScript = "chrome://browser/content/tabview-content.js";
       gWindow.messageManager.loadFrameScript(frameScript, true);
       // ___ Done
       this._frameInitialized = true;
       this._save();
       // fire an iframe initialized event so everyone knows tab view is
       // initialized.
       let event = document.createEvent("Events");
       event.initEvent("tabviewframeinitialized", true, false);
       dispatchEvent(event);
     } catch(e) {
       Utils.log(e);
     } finally {
       GroupItems.resumeArrange();
     }
   },
   // Function: uninit
   // Should be called when window is unloaded.
   uninit: function UI_uninit() {
     // call our cleanup functions
     this._cleanupFunctions.forEach(function(func) {
       func();
     });
     this._cleanupFunctions = [];
     // additional clean up
     TabItems.uninit();
     GroupItems.uninit();
     FavIcons.uninit();
     Storage.uninit();
     Telemetry.uninit();
     this._removeTabActionHandlers();
     this._currentTab = null;
     this._pageBounds = null;
     this._reorderTabItemsOnShow = null;
     this._reorderTabsOnHide = null;
     this._frameInitialized = false;
   },
   // Property: rtl
   // Returns true if we are in RTL mode, false otherwise
   rtl: false,
   // Function: reset
   // Resets the Panorama view to have just one group with all tabs
   reset: function UI_reset() {
     let padding = Trenches.defaultRadius;
     let welcomeWidth = 300;
     let pageBounds = Items.getPageBounds();
     pageBounds.inset(padding, padding);
     let $actions = iQ("#actions");
     if ($actions) {
       pageBounds.width -= $actions.width();
       if (UI.rtl)
         pageBounds.left += $actions.width() - padding;
     }
     // ___ make a fresh groupItem
     let box = new Rect(pageBounds);
     box.width = Math.min(box.width * 0.667,
                          pageBounds.width - (welcomeWidth + padding));
     box.height = box.height * 0.667;
     if (UI.rtl) {
       box.left = pageBounds.left + welcomeWidth + 2 * padding;
     }
     GroupItems.groupItems.forEach(function(group) {
       group.close();
     });
     let options = {
       bounds: box,
       immediately: true
     };
     let groupItem = new GroupItem([], options);
     let items = TabItems.getItems();
     items.forEach(function(item) {
       if (item.parent)
         item.parent.remove(item);
       groupItem.add(item, {immediately: true});
     });
     this.setActive(groupItem);
   },
   // ----------
   // Function: blurAll
   // Blurs any currently focused element
   blurAll: function UI_blurAll() {
     iQ(":focus").each(function(element) {
       element.blur();
     });
   },
   // ----------
   // Function: isIdle
   // Returns true if the last interaction was long enough ago to consider the
   // UI idle. Used to determine whether interactivity would be sacrificed if
   // the CPU was to become busy.
   //
   isIdle: function UI_isIdle() {
     let time = Date.now();
     let maxEvent = Math.max(drag.lastMoveTime, resize.lastMoveTime);
     return (time - maxEvent) > this._maxInteractiveWait;
   },
   // ----------
   // Function: getActiveTab
   // Returns the currently active tab as a <TabItem>
   getActiveTab: function UI_getActiveTab() {
     return this._activeTab;
   },
   // ----------
   // Function: _setActiveTab
   // Sets the currently active tab. The idea of a focused tab is useful
   // for keyboard navigation and returning to the last zoomed-in tab.
   // Hitting return/esc brings you to the focused tab, and using the
   // arrow keys lets you navigate between open tabs.
   //
   // Parameters:
   //  - Takes a <TabItem>
   _setActiveTab: function UI__setActiveTab(tabItem) {
     if (tabItem == this._activeTab)
       return;
     if (this._activeTab) {
       this._activeTab.makeDeactive();
       this._activeTab.removeSubscriber("close", this._onActiveTabClosed);
     }
     this._activeTab = tabItem;
     if (this._activeTab) {
       this._activeTab.addSubscriber("close", this._onActiveTabClosed);
       this._activeTab.makeActive();
     }
   },
   // ----------
   // Function: _onActiveTabClosed
   // Handles when the currently active tab gets closed.
   //
   // Parameters:
   //  - the <TabItem> that is closed
   _onActiveTabClosed: function UI__onActiveTabClosed(tabItem){
     if (UI._activeTab == tabItem)
       UI._setActiveTab(null);
   },
   // ----------
   // Function: setActive
   // Sets the active tab item or group item
   // Parameters:
   //
   // options
   //  dontSetActiveTabInGroup bool for not setting active tab in group
   setActive: function UI_setActive(item, options) {
     Utils.assert(item, "item must be given");
     if (item.isATabItem) {
       if (item.parent)
         GroupItems.setActiveGroupItem(item.parent);
       if (!options || !options.dontSetActiveTabInGroup)
         this._setActiveTab(item);
     } else {
       GroupItems.setActiveGroupItem(item);
       if (!options || !options.dontSetActiveTabInGroup) {
         let activeTab = item.getActiveTab();
         if (activeTab)
           this._setActiveTab(activeTab);
       }
     }
   },
   // ----------
   // Function: clearActiveTab
   // Sets the active tab to 'null'.
   clearActiveTab: function UI_clearActiveTab() {
     this._setActiveTab(null);
   },
   // ----------
   // Function: isTabViewVisible
   // Returns true if the TabView UI is currently shown.
   isTabViewVisible: function UI_isTabViewVisible() {
     return gTabViewDeck.selectedPanel == gTabViewFrame;
   },
   // ---------
   // Function: _initPageDirection
   // Initializes the page base direction
   _initPageDirection: function UI__initPageDirection() {
     let chromeReg = Cc["@mozilla.org/chrome/chrome-registry;1"].
                     getService(Ci.nsIXULChromeRegistry);
     let dir = chromeReg.isLocaleRTL("global");
     document.documentElement.setAttribute("dir", dir ? "rtl" : "ltr");
     this.rtl = dir;
   },
   // ----------
   // Function: showTabView
   // Shows TabView and hides the main browser UI.
   // Parameters:
   //   zoomOut - true for zoom out animation, false for nothing.
   showTabView: function UI_showTabView(zoomOut) {
     if (this.isTabViewVisible() || this._isChangingVisibility)
       return;
     this._isChangingVisibility = true;
     // store tab strip smooth scroll value and disable it.
     let tabStrip = gBrowser.tabContainer.mTabstrip;
     this._originalSmoothScroll = tabStrip.smoothScroll;
     tabStrip.smoothScroll = false;
     // initialize the direction of the page
     this._initPageDirection();
     var self = this;
     var currentTab = this._currentTab;
     this._reorderTabItemsOnShow.forEach(function(groupItem) {
       groupItem.reorderTabItemsBasedOnTabOrder();
     });
     this._reorderTabItemsOnShow = [];
 #ifdef XP_WIN
     // Restore the full height when showing TabView
     gTabViewFrame.style.marginTop = "";
 #endif
     gTabViewDeck.selectedPanel = gTabViewFrame;
     gWindow.TabsInTitlebar.allowedBy("tabview-open", false);
     gTabViewFrame.contentWindow.focus();
     gBrowser.updateTitlebar();
 #ifdef XP_MACOSX
     this.setTitlebarColors(true);
 #endif
     let event = document.createEvent("Events");
     event.initEvent("tabviewshown", true, false);
     Storage.saveVisibilityData(gWindow, "true");
     if (zoomOut && currentTab && currentTab._tabViewTabItem) {
       let item = currentTab._tabViewTabItem;
       // If there was a previous currentTab we want to animate
       // its thumbnail (canvas) for the zoom out.
       // Note that we start the animation on the chrome thread.
       // Zoom out!
       item.zoomOut(function() {
         if (!currentTab._tabViewTabItem) // if the tab's been destroyed
           item = null;
         self.setActive(item);
         self._resize(true);
         self._isChangingVisibility = false;
         dispatchEvent(event);
         // Flush pending updates
         GroupItems.flushAppTabUpdates();
         TabItems.resumePainting();
       });
     } else {
       if (!currentTab || !currentTab._tabViewTabItem)
         self.clearActiveTab();
       self._isChangingVisibility = false;
       dispatchEvent(event);
       // Flush pending updates
       GroupItems.flushAppTabUpdates();
       TabItems.resumePainting();
     }
     if (gTabView.firstUseExperienced)
       gTabView.enableSessionRestore();
   },
   // ----------
   // Function: hideTabView
   // Hides TabView and shows the main browser UI.
   hideTabView: function UI_hideTabView() {
     if (!this.isTabViewVisible() || this._isChangingVisibility)
       return;
     // another tab might be select if user decides to stay on a page when
     // a onclose confirmation prompts.
     GroupItems.removeHiddenGroups();
     // We need to set this after removing the hidden groups because doing so
     // might show prompts which will cause us to be called again, and we'd get
     // stuck if we prevent re-entrancy before doing that.
     this._isChangingVisibility = true;
     TabItems.pausePainting();
     this._reorderTabsOnHide.forEach(function(groupItem) {
       groupItem.reorderTabsBasedOnTabItemOrder();
     });
     this._reorderTabsOnHide = [];
 #ifdef XP_WIN
     // Push the top of TabView frame to behind the tabbrowser, so glass can show
     // XXX bug 586679: avoid shrinking the iframe and squishing iframe contents
     // as well as avoiding the flash of black as we animate out
     gTabViewFrame.style.marginTop = gBrowser.boxObject.y + "px";
 #endif
     gTabViewDeck.selectedPanel = gBrowserPanel;
     gWindow.TabsInTitlebar.allowedBy("tabview-open", true);
     gBrowser.selectedBrowser.focus();
     gBrowser.updateTitlebar();
     gBrowser.tabContainer.mTabstrip.smoothScroll = this._originalSmoothScroll;
 #ifdef XP_MACOSX
     this.setTitlebarColors(false);
 #endif
     Storage.saveVisibilityData(gWindow, "false");
     this._isChangingVisibility = false;
     let event = document.createEvent("Events");
     event.initEvent("tabviewhidden", true, false);
     dispatchEvent(event);
   },
 #ifdef XP_MACOSX
   // ----------
   // Function: setTitlebarColors
   // Used on the Mac to make the title bar match the gradient in the rest of the
   // TabView UI.
   //
   // Parameters:
   //   colors - (bool or object) true for the special TabView color, false for
   //         the normal color, and an object with "active" and "inactive"
   //         properties to specify directly.
   setTitlebarColors: function UI_setTitlebarColors(colors) {
     // Mac Only
     var mainWindow = gWindow.document.getElementById("main-window");
     if (colors === true) {
       mainWindow.setAttribute("activetitlebarcolor", "#C4C4C4");
       mainWindow.setAttribute("inactivetitlebarcolor", "#EDEDED");
     } else if (colors && "active" in colors && "inactive" in colors) {
       mainWindow.setAttribute("activetitlebarcolor", colors.active);
       mainWindow.setAttribute("inactivetitlebarcolor", colors.inactive);
     } else {
       mainWindow.removeAttribute("activetitlebarcolor");
       mainWindow.removeAttribute("inactivetitlebarcolor");
     }
   },
 #endif
   // ----------
   // Function: storageBusy
   // Pauses the storage activity that conflicts with sessionstore updates.
   // Calls can be nested.
   storageBusy: function UI_storageBusy() {
     if (this._storageBusy)
       return;
     this._storageBusy = true;
     TabItems.pauseReconnecting();
     GroupItems.pauseAutoclose();
   },
   // ----------
   // Function: storageReady
   // Resumes the activity paused by storageBusy, and updates for any new group
   // information in sessionstore. Calls can be nested.
   storageReady: function UI_storageReady() {
     if (!this._storageBusy)
       return;
     this._storageBusy = false;
     let hasGroupItemsData = GroupItems.load();
     if (!hasGroupItemsData)
       this.reset();
     TabItems.resumeReconnecting();
     GroupItems._updateTabBar();
     GroupItems.resumeAutoclose();
   },
   // ----------
   // Function: _addTabActionHandlers
   // Adds handlers to handle tab actions.
   _addTabActionHandlers: function UI__addTabActionHandlers() {
     var self = this;
     // session restore events
     function handleSSWindowStateBusy() {
       self.storageBusy();
     }
     function handleSSWindowStateReady() {
       self.storageReady();
     }
     gWindow.addEventListener("SSWindowStateBusy", handleSSWindowStateBusy, false);
     gWindow.addEventListener("SSWindowStateReady", handleSSWindowStateReady, false);
     this._cleanupFunctions.push(function() {
       gWindow.removeEventListener("SSWindowStateBusy", handleSSWindowStateBusy, false);
       gWindow.removeEventListener("SSWindowStateReady", handleSSWindowStateReady, false);
     });
     // TabOpen
     this._eventListeners.open = function (event) {
       let tab = event.target;
       // if it's an app tab, add it to all the group items
       if (tab.pinned)
         GroupItems.addAppTab(tab);
       else if (self.isTabViewVisible() && !self._storageBusyCount)
         self._lastOpenedTab = tab;
     };
     // TabClose
     this._eventListeners.close = function (event) {
       let tab = event.target;
       // if it's an app tab, remove it from all the group items
       if (tab.pinned)
         GroupItems.removeAppTab(tab);
       if (self.isTabViewVisible()) {
         // just closed the selected tab in the TabView interface.
         if (self._currentTab == tab)
           self._closedSelectedTabInTabView = true;
       } else {
         // If we're currently in the process of session store update,
         // we don't want to go to the Tab View UI.
         if (self._storageBusy)
           return;
         // if not closing the last tab
         if (gBrowser.tabs.length > 1) {
           // Don't return to TabView if there are any app tabs
           for (let a = 0; a < gBrowser._numPinnedTabs; a++) {
             if (Utils.isValidXULTab(gBrowser.tabs[a]))
               return;
           }
           let groupItem = GroupItems.getActiveGroupItem();
           // 1) Only go back to the TabView tab when there you close the last
           // tab of a groupItem.
           let closingLastOfGroup = (groupItem &&
               groupItem._children.length == 1 &&
               groupItem._children[0].tab == tab);
           // 2) When a blank tab is active while restoring a closed tab the
           // blank tab gets removed. The active group is not closed as this is
           // where the restored tab goes. So do not show the TabView.
           let tabItem = tab && tab._tabViewTabItem;
           let closingBlankTabAfterRestore =
             (tabItem && tabItem.isRemovedAfterRestore);
           if (closingLastOfGroup && !closingBlankTabAfterRestore) {
             // for the tab focus event to pick up.
             self._closedLastVisibleTab = true;
             self.showTabView();
           }
         }
       }
     };
     // TabMove
     this._eventListeners.move = function (event) {
       let tab = event.target;
       if (GroupItems.groupItems.length > 0) {
         if (tab.pinned) {
           if (gBrowser._numPinnedTabs > 1)
             GroupItems.arrangeAppTab(tab);
         } else {
           let activeGroupItem = GroupItems.getActiveGroupItem();
           if (activeGroupItem)
             self.setReorderTabItemsOnShow(activeGroupItem);
         }
       }
     };
     // TabSelect
     this._eventListeners.select = function (event) {
       self.onTabSelect(event.target);
     };
     // TabPinned
     this._eventListeners.pinned = function (event) {
       let tab = event.target;
       TabItems.handleTabPin(tab);
       GroupItems.addAppTab(tab);
     };
     // TabUnpinned
     this._eventListeners.unpinned = function (event) {
       let tab = event.target;
       TabItems.handleTabUnpin(tab);
       GroupItems.removeAppTab(tab);
       let groupItem = tab._tabViewTabItem.parent;
       if (groupItem)
         self.setReorderTabItemsOnShow(groupItem);
     };
     // Actually register the above handlers
     for (let name in this._eventListeners)
       AllTabs.register(name, this._eventListeners[name]);
   },
   // ----------
   // Function: _removeTabActionHandlers
   // Removes handlers to handle tab actions.
   _removeTabActionHandlers: function UI__removeTabActionHandlers() {
     for (let name in this._eventListeners)
       AllTabs.unregister(name, this._eventListeners[name]);
   },
   // ----------
   // Function: goToTab
   // Selects the given xul:tab in the browser.
   goToTab: function UI_goToTab(xulTab) {
     // If it's not focused, the onFocus listener would handle it.
     if (xulTab.selected)
       this.onTabSelect(xulTab);
     else
       gBrowser.selectedTab = xulTab;
   },
   // ----------
   // Function: onTabSelect
   // Called when the user switches from one tab to another outside of the TabView UI.
   onTabSelect: function UI_onTabSelect(tab) {
     this._currentTab = tab;
     if (this.isTabViewVisible()) {
       // We want to zoom in if:
       // 1) we didn't just restore a tab via Ctrl+Shift+T
       // 2) the currently selected tab is the last created tab and has a tabItem
       if (!this.restoredClosedTab &&
           this._lastOpenedTab == tab && tab._tabViewTabItem) {
         tab._tabViewTabItem.zoomIn(true);
         this._lastOpenedTab = null;
         return;
       }
       if (this._closedLastVisibleTab ||
           (this._closedSelectedTabInTabView && !this.closedLastTabInTabView) ||
           this.restoredClosedTab) {
         if (this.restoredClosedTab) {
           // when the tab view UI is being displayed, update the thumb for the
           // restored closed tab after the page load
           tab.linkedBrowser.addEventListener("load", function onLoad(event) {
             tab.linkedBrowser.removeEventListener("load", onLoad, true);
             TabItems._update(tab);
           }, true);
         }
         this._closedLastVisibleTab = false;
         this._closedSelectedTabInTabView = false;
         this.closedLastTabInTabView = false;
         this.restoredClosedTab = false;
         return;
       }
     }
     // reset these vars, just in case.
     this._closedLastVisibleTab = false;
     this._closedSelectedTabInTabView = false;
     this.closedLastTabInTabView = false;
     this.restoredClosedTab = false;
     this._lastOpenedTab = null;
     // if TabView is visible but we didn't just close the last tab or
     // selected tab, show chrome.
     if (this.isTabViewVisible()) {
       // Unhide the group of the tab the user is activating.
       if (tab && tab._tabViewTabItem && tab._tabViewTabItem.parent &&
           tab._tabViewTabItem.parent.hidden)
         tab._tabViewTabItem.parent._unhide({immediately: true});
       this.hideTabView();
     }
     // another tab might be selected when hideTabView() is invoked so a
     // validation is needed.
     if (this._currentTab != tab)
       return;
     let newItem = null;
     // update the tab bar for the new tab's group
     if (tab && tab._tabViewTabItem) {
       if (!TabItems.reconnectingPaused()) {
         newItem = tab._tabViewTabItem;
         GroupItems.updateActiveGroupItemAndTabBar(newItem);
       }
     } else {
       // No tabItem; must be an app tab. Base the tab bar on the current group.
       // If no current group, figure it out based on what's already in the tab
       // bar.
       if (!GroupItems.getActiveGroupItem()) {
         for (let a = 0; a < gBrowser.tabs.length; a++) {
           let theTab = gBrowser.tabs[a];
           if (!theTab.pinned) {
             let tabItem = theTab._tabViewTabItem;
             this.setActive(tabItem.parent);
             break;
           }
         }
       }
       if (GroupItems.getActiveGroupItem())
         GroupItems._updateTabBar();
     }
   },
   // ----------
   // Function: _onDOMWillOpenModalDialog
   // Called when a web page is about to show a modal dialog.
   _onDOMWillOpenModalDialog: function UI__onDOMWillOpenModalDialog(cx) {
     if (!this.isTabViewVisible())
       return;
     let index = gBrowser.browsers.indexOf(cx.target);
     if (index == -1)
       return;
     let tab = gBrowser.tabs[index];
     // When TabView is visible, we need to call onTabSelect to make sure that
     // TabView is hidden and that the correct group is activated. When a modal
     // dialog is shown for currently selected tab the onTabSelect event handler
     // is not called, so we need to do it.
     if (tab.selected && this._currentTab == tab)
       this.onTabSelect(tab);
   },
   // ----------
   // Function: setReorderTabsOnHide
   // Sets the groupItem which the tab items' tabs should be re-ordered when
   // switching to the main browser UI.
   // Parameters:
   //   groupItem - the groupItem which would be used for re-ordering tabs.
   setReorderTabsOnHide: function UI_setReorderTabsOnHide(groupItem) {
     if (this.isTabViewVisible()) {
       var index = this._reorderTabsOnHide.indexOf(groupItem);
       if (index == -1)
         this._reorderTabsOnHide.push(groupItem);
     }
   },
   // ----------
   // Function: setReorderTabItemsOnShow
   // Sets the groupItem which the tab items should be re-ordered when
   // switching to the tab view UI.
   // Parameters:
   //   groupItem - the groupItem which would be used for re-ordering tab items.
   setReorderTabItemsOnShow: function UI_setReorderTabItemsOnShow(groupItem) {
     if (!this.isTabViewVisible()) {
       var index = this._reorderTabItemsOnShow.indexOf(groupItem);
       if (index == -1)
         this._reorderTabItemsOnShow.push(groupItem);
     }
   },
   // ----------
   updateTabButton: function UI_updateTabButton() {
     let exitButton = document.getElementById("exit-button");
     let numberOfGroups = GroupItems.groupItems.length;
     exitButton.setAttribute("groups", numberOfGroups);
     gTabView.updateGroupNumberBroadcaster(numberOfGroups);
   },
   // ----------
   // Function: getClosestTab
   // Convenience function to get the next tab closest to the entered position
   getClosestTab: function UI_getClosestTab(tabCenter) {
     let cl = null;
     let clDist;
     TabItems.getItems().forEach(function (item) {
       if (!item.parent || item.parent.hidden)
         return;
       let testDist = tabCenter.distance(item.bounds.center());
       if (cl==null || testDist < clDist) {
         cl = item;
         clDist = testDist;
       }
     });
     return cl;
   },
   // ----------
   // Function: _setupBrowserKeys
   // Sets up the allowed browser keys using key elements.
   _setupBrowserKeys: function UI__setupKeyWhiteList() {
     let keys = {};
     [
 #ifdef XP_UNIX
       "quitApplication",
 #else
       "redo",
 #endif
 #ifdef XP_MACOSX
       "preferencesCmdMac", "minimizeWindow", "hideThisAppCmdMac",
 #endif
       "newNavigator", "newNavigatorTab", "undo", "cut", "copy", "paste",
       "selectAll", "find"
     ].forEach(function(key) {
       let element = gWindow.document.getElementById("key_" + key);
       let code = element.getAttribute("key").toLocaleLowerCase().charCodeAt(0);
       keys[code] = key;
     });
     this._browserKeys = keys;
     keys = {};
     // The lower case letters are passed to processBrowserKeys() even with shift
     // key when stimulating a key press using EventUtils.synthesizeKey() so need
     // to handle both upper and lower cases here.
     [
 #ifdef XP_UNIX
       "redo",
 #endif
 #ifdef XP_MACOSX
       "fullScreen",
 #endif
       "closeWindow", "tabview", "undoCloseTab", "undoCloseWindow"
     ].forEach(function(key) {
       let element = gWindow.document.getElementById("key_" + key);
       let code = element.getAttribute("key").toLocaleLowerCase().charCodeAt(0);
       keys[code] = key;
     });
     this._browserKeysWithShift = keys;
   },
   // ----------
   // Function: _setTabViewFrameKeyHandlers
   // Sets up the key handlers for navigating between tabs within the TabView UI.
   _setTabViewFrameKeyHandlers: function UI__setTabViewFrameKeyHandlers() {
     let self = this;
     this._setupBrowserKeys();
     iQ(window).keyup(function(event) {
       if (!event.metaKey)
         Keys.meta = false;
     });
     iQ(window).keypress(function(event) {
       if (event.metaKey)
         Keys.meta = true;
       function processBrowserKeys(evt) {
         // let any keys with alt to pass through
         if (evt.altKey)
           return;
 #ifdef XP_MACOSX
         if (evt.metaKey) {
 #else
         if (evt.ctrlKey) {
 #endif
           let preventDefault = true;
           if (evt.shiftKey) {
             // when a user presses ctrl+shift+key, upper case letter charCode
             // is passed to processBrowserKeys() so converting back to lower
             // case charCode before doing the check
             let lowercaseCharCode =
               String.fromCharCode(evt.charCode).toLocaleLowerCase().charCodeAt(0);
             if (lowercaseCharCode in self._browserKeysWithShift) {
               let key = self._browserKeysWithShift[lowercaseCharCode];
               if (key == "tabview")
                 self.exit();
               else
                 preventDefault = false;
             }
           } else {
             if (evt.charCode in self._browserKeys) {
               let key = self._browserKeys[evt.charCode];
               if (key == "find")
                 self.enableSearch();
               else
                 preventDefault = false;
             }
           }
           if (preventDefault) {
             evt.stopPropagation();
             evt.preventDefault();
           }
         }
       }
       if ((iQ(":focus").length > 0 && iQ(":focus")[0].nodeName == "INPUT") ||
           Search.isEnabled() || self.ignoreKeypressForSearch) {
         self.ignoreKeypressForSearch = false;
         processBrowserKeys(event);
         return;
       }
       function getClosestTabBy(norm) {
         if (!self.getActiveTab())
           return null;
         let activeTab = self.getActiveTab();
         let activeTabGroup = activeTab.parent;
         let myCenter = activeTab.bounds.center();
         let match;
         TabItems.getItems().forEach(function (item) {
           if (!item.parent.hidden &&
               (!activeTabGroup.expanded || activeTabGroup.id == item.parent.id)) {
             let itemCenter = item.bounds.center();
             if (norm(itemCenter, myCenter)) {
               let itemDist = myCenter.distance(itemCenter);
               if (!match || match[0] > itemDist)
                 match = [itemDist, item];
             }
           }
         });
         return match && match[1];
       }
       let preventDefault = true;
       let activeTab;
       let activeGroupItem;
       let norm = null;
       switch (event.keyCode) {
         case KeyEvent.DOM_VK_RIGHT:
           norm = function(a, me){return a.x > me.x};
           break;
         case KeyEvent.DOM_VK_LEFT:
           norm = function(a, me){return a.x < me.x};
           break;
         case KeyEvent.DOM_VK_DOWN:
           norm = function(a, me){return a.y > me.y};
           break;
         case KeyEvent.DOM_VK_UP:
           norm = function(a, me){return a.y < me.y}
           break;
       }
       if (norm != null) {
         let nextTab = getClosestTabBy(norm);
         if (nextTab) {
           if (nextTab.isStacked && !nextTab.parent.expanded)
             nextTab = nextTab.parent.getChild(0);
           self.setActive(nextTab);
         }
       } else {
         switch(event.keyCode) {
           case KeyEvent.DOM_VK_ESCAPE:
             activeGroupItem = GroupItems.getActiveGroupItem();
             if (activeGroupItem && activeGroupItem.expanded)
               activeGroupItem.collapse();
             else
               self.exit();
             break;
           case KeyEvent.DOM_VK_RETURN:
             activeGroupItem = GroupItems.getActiveGroupItem();
             if (activeGroupItem) {
               activeTab = self.getActiveTab();
               if (!activeTab || activeTab.parent != activeGroupItem)
                 activeTab = activeGroupItem.getActiveTab();
               if (activeTab)
                 activeTab.zoomIn();
               else
                 activeGroupItem.newTab();
             }
             break;
           case KeyEvent.DOM_VK_TAB:
             // tab/shift + tab to go to the next tab.
             activeTab = self.getActiveTab();
             if (activeTab) {
               let tabItems = (activeTab.parent ? activeTab.parent.getChildren() :
                               [activeTab]);
               let length = tabItems.length;
               let currentIndex = tabItems.indexOf(activeTab);
               if (length > 1) {
                 let newIndex;
                 if (event.shiftKey) {
                   if (currentIndex == 0)
                     newIndex = (length - 1);
                   else
                     newIndex = (currentIndex - 1);
                 } else {
                   if (currentIndex == (length - 1))
                     newIndex = 0;
                   else
                     newIndex = (currentIndex + 1);
                 }
                 self.setActive(tabItems[newIndex]);
               }
             }
             break;
           default:
             processBrowserKeys(event);
             preventDefault = false;
         }
         if (preventDefault) {
           event.stopPropagation();
           event.preventDefault();
         }
       }
     });
   },
   // ----------
   // Function: enableSearch
   // Enables the search feature.
   enableSearch: function UI_enableSearch() {
     if (!Search.isEnabled()) {
       Search.ensureShown();
       Search.switchToInMode();
     }
   },
   // ----------
   // Function: _createGroupItemOnDrag
   // Called in response to a mousedown in empty space in the TabView UI;
   // creates a new groupItem based on the user's drag.
   _createGroupItemOnDrag: function UI__createGroupItemOnDrag(e) {
     const minSize = 60;
     const minMinSize = 15;
     let lastActiveGroupItem = GroupItems.getActiveGroupItem();
     var startPos = { x: e.clientX, y: e.clientY };
     var phantom = iQ("<div>")
       .addClass("groupItem phantom activeGroupItem dragRegion")
       .css({
         position: "absolute",
         zIndex: -1,
         cursor: "default"
       })
       .appendTo("body");
     var item = { // a faux-Item
       container: phantom,
       isAFauxItem: true,
       bounds: {},
       getBounds: function FauxItem_getBounds() {
         return this.container.bounds();
       },
       setBounds: function FauxItem_setBounds(bounds) {
         this.container.css(bounds);
       },
       setZ: function FauxItem_setZ(z) {
         // don't set a z-index because we want to force it to be low.
       },
       setOpacity: function FauxItem_setOpacity(opacity) {
         this.container.css("opacity", opacity);
       },
       // we don't need to pushAway the phantom item at the end, because
       // when we create a new GroupItem, it'll do the actual pushAway.
       pushAway: function () {},
     };
     item.setBounds(new Rect(startPos.y, startPos.x, 0, 0));
     var dragOutInfo = new Drag(item, e);
     function updateSize(e) {
       var box = new Rect();
       box.left = Math.min(startPos.x, e.clientX);
       box.right = Math.max(startPos.x, e.clientX);
       box.top = Math.min(startPos.y, e.clientY);
       box.bottom = Math.max(startPos.y, e.clientY);
       item.setBounds(box);
       // compute the stationaryCorner
       var stationaryCorner = "";
       if (startPos.y == box.top)
         stationaryCorner += "top";
       else
         stationaryCorner += "bottom";
       if (startPos.x == box.left)
         stationaryCorner += "left";
       else
         stationaryCorner += "right";
       dragOutInfo.snap(stationaryCorner, false, false); // null for ui, which we don't use anyway.
       box = item.getBounds();
       if (box.width > minMinSize && box.height > minMinSize &&
          (box.width > minSize || box.height > minSize))
         item.setOpacity(1);
       else
         item.setOpacity(0.7);
       e.preventDefault();
     }
     let self = this;
     function collapse() {
       let center = phantom.bounds().center();
       phantom.animate({
         width: 0,
         height: 0,
         top: center.y,
         left: center.x
       }, {
         duration: 300,
         complete: function() {
           phantom.remove();
         }
       });
       self.setActive(lastActiveGroupItem);
     }
     function finalize(e) {
       iQ(window).unbind("mousemove", updateSize);
       item.container.removeClass("dragRegion");
       dragOutInfo.stop();
       let box = item.getBounds();
       if (box.width > minMinSize && box.height > minMinSize &&
          (box.width > minSize || box.height > minSize)) {
         let opts = {bounds: item.getBounds(), focusTitle: true};
         let groupItem = new GroupItem([], opts);
         self.setActive(groupItem);
         phantom.remove();
         dragOutInfo = null;
         gTabView.firstUseExperienced = true;
       } else {
         collapse();
       }
     }
     iQ(window).mousemove(updateSize)
     iQ(gWindow).one("mouseup", finalize);
     e.preventDefault();
     return false;
   },
   // ----------
   // Function: _resize
   // Update the TabView UI contents in response to a window size change.
   // Won't do anything if it doesn't deem the resize necessary.
   // Parameters:
   //   force - true to update even when "unnecessary"; default false
   _resize: function UI__resize(force) {
     if (!this._pageBounds)
       return;
     // Here are reasons why we *won't* resize:
     // 1. Panorama isn't visible (in which case we will resize when we do display)
     // 2. the screen dimensions haven't changed
     // 3. everything on the screen fits and nothing feels cramped
     if (!force && !this.isTabViewVisible())
       return;
     let oldPageBounds = new Rect(this._pageBounds);
     let newPageBounds = Items.getPageBounds();
     if (newPageBounds.equals(oldPageBounds))
       return;
     if (!this.shouldResizeItems())
       return;
     var items = Items.getTopLevelItems();
     // compute itemBounds: the union of all the top-level items' bounds.
     var itemBounds = new Rect(this._pageBounds);
     // We start with pageBounds so that we respect the empty space the user
     // has left on the page.
     itemBounds.width = 1;
     itemBounds.height = 1;
     items.forEach(function(item) {
       var bounds = item.getBounds();
       itemBounds = (itemBounds ? itemBounds.union(bounds) : new Rect(bounds));
     });
     if (newPageBounds.width < this._pageBounds.width &&
         newPageBounds.width > itemBounds.width)
       newPageBounds.width = this._pageBounds.width;
     if (newPageBounds.height < this._pageBounds.height &&
         newPageBounds.height > itemBounds.height)
       newPageBounds.height = this._pageBounds.height;
     var wScale;
     var hScale;
     if (Math.abs(newPageBounds.width - this._pageBounds.width)
          > Math.abs(newPageBounds.height - this._pageBounds.height)) {
       wScale = newPageBounds.width / this._pageBounds.width;
       hScale = newPageBounds.height / itemBounds.height;
     } else {
       wScale = newPageBounds.width / itemBounds.width;
       hScale = newPageBounds.height / this._pageBounds.height;
     }
     var scale = Math.min(hScale, wScale);
     var self = this;
     var pairs = [];
     items.forEach(function(item) {
       var bounds = item.getBounds();
       bounds.left += (UI.rtl ? -1 : 1) * (newPageBounds.left - self._pageBounds.left);
       bounds.left *= scale;
       bounds.width *= scale;
       bounds.top += newPageBounds.top - self._pageBounds.top;
       bounds.top *= scale;
       bounds.height *= scale;
       pairs.push({
         item: item,
         bounds: bounds
       });
     });
     Items.unsquish(pairs);
     pairs.forEach(function(pair) {
       pair.item.setBounds(pair.bounds, true);
       pair.item.snap();
     });
     this._pageBounds = Items.getPageBounds();
     this._save();
   },
   // ----------
   // Function: shouldResizeItems
   // Returns whether we should resize the items on the screen, based on whether
   // the top-level items fit in the screen or not and whether they feel
   // "cramped" or not.
   // These computations may be done using cached values. The cache can be
   // cleared with UI.clearShouldResizeItems().
   shouldResizeItems: function UI_shouldResizeItems() {
     let newPageBounds = Items.getPageBounds();
     // If we don't have cached cached values...
     if (this._minimalRect === undefined || this._feelsCramped === undefined) {
       // Loop through every top-level Item for two operations:
       // 1. check if it is feeling "cramped" due to squishing (a technical term),
       // 2. union its bounds with the minimalRect
       let feelsCramped = false;
       let minimalRect = new Rect(0, 0, 1, 1);
       Items.getTopLevelItems()
         .forEach(function UI_shouldResizeItems_checkItem(item) {
           let bounds = new Rect(item.getBounds());
           feelsCramped = feelsCramped || (item.userSize &&
             (item.userSize.x > bounds.width || item.userSize.y > bounds.height));
           bounds.inset(-Trenches.defaultRadius, -Trenches.defaultRadius);
           minimalRect = minimalRect.union(bounds);
         });
       // ensure the minimalRect extends to, but not beyond, the origin
       minimalRect.left = 0;
       minimalRect.top  = 0;
       this._minimalRect = minimalRect;
       this._feelsCramped = feelsCramped;
     }
     return this._minimalRect.width > newPageBounds.width ||
       this._minimalRect.height > newPageBounds.height ||
       this._feelsCramped;
   },
   // ----------
   // Function: clearShouldResizeItems
   // Clear the cache of whether we should resize the items on the Panorama
   // screen, forcing a recomputation on the next UI.shouldResizeItems()
   // call.
   clearShouldResizeItems: function UI_clearShouldResizeItems() {
     delete this._minimalRect;
     delete this._feelsCramped;
   },
   // ----------
   // Function: exit
   // Exits TabView UI.
   exit: function UI_exit() {
     let self = this;
     let zoomedIn = false;
     if (Search.isEnabled()) {
       let matcher = Search.createSearchTabMatcher();
       let matches = matcher.matched();
       if (matches.length > 0) {
         matches[0].zoomIn();
         zoomedIn = true;
       }
       Search.hide();
     }
     if (!zoomedIn) {
       let unhiddenGroups = GroupItems.groupItems.filter(function(groupItem) {
         return (!groupItem.hidden && groupItem.getChildren().length > 0);
       });
       // no pinned tabs and no visible groups: open a new group. open a blank
       // tab and return
       if (!unhiddenGroups.length) {
         let emptyGroups = GroupItems.groupItems.filter(function (groupItem) {
           return (!groupItem.hidden && !groupItem.getChildren().length);
         });
         let group = (emptyGroups.length ? emptyGroups[0] : GroupItems.newGroup());
         if (!gBrowser._numPinnedTabs) {
           group.newTab(null, { closedLastTab: true });
           return;
         }
       }
       // If there's an active TabItem, zoom into it. If not (for instance when the
       // selected tab is an app tab), just go there.
       let activeTabItem = this.getActiveTab();
       if (!activeTabItem) {
         let tabItem = gBrowser.selectedTab._tabViewTabItem;
         if (tabItem) {
           if (!tabItem.parent || !tabItem.parent.hidden) {
             activeTabItem = tabItem;
           } else { // set active tab item if there is at least one unhidden group
             if (unhiddenGroups.length > 0)
               activeTabItem = unhiddenGroups[0].getActiveTab();
           }
         }
       }
       if (activeTabItem) {
         activeTabItem.zoomIn();
       } else {
         if (gBrowser._numPinnedTabs > 0) {
           if (gBrowser.selectedTab.pinned) {
             self.goToTab(gBrowser.selectedTab);
           } else {
             Array.some(gBrowser.tabs, function(tab) {
               if (tab.pinned) {
                 self.goToTab(tab);
                 return true;
               }
               return false
             });
           }
         }
       }
     }
   },
   // ----------
   // Function: storageSanity
   // Given storage data for this object, returns true if it looks valid.
   _storageSanity: function UI__storageSanity(data) {
     if (Utils.isEmptyObject(data))
       return true;
     if (!Utils.isRect(data.pageBounds)) {
       Utils.log("UI.storageSanity: bad pageBounds", data.pageBounds);
       data.pageBounds = null;
       return false;
     }
     return true;
   },
   // ----------
   // Function: _save
   // Saves the data for this object to persistent storage
   _save: function UI__save() {
     if (!this._frameInitialized)
       return;
     var data = {
       pageBounds: this._pageBounds
     };
     if (this._storageSanity(data))
       Storage.saveUIData(gWindow, data);
   },
   // ----------
   // Function: _saveAll
   // Saves all data associated with TabView.
   _saveAll: function UI__saveAll() {
     this._save();
     GroupItems.saveAll();
     TabItems.saveAll();
   },
   // ----------
   // Function: notifySessionRestoreEnabled
   // Notify the user that session restore has been automatically enabled
   // by showing a banner that expects no user interaction. It fades out after
   // some seconds.
   notifySessionRestoreEnabled: function UI_notifySessionRestoreEnabled() {
     let brandBundle = gWindow.document.getElementById("bundle_brand");
     let brandShortName = brandBundle.getString("brandShortName");
     let notificationText = tabviewBundle.formatStringFromName(
       "tabview.notification.sessionStore", [brandShortName], 1);
     let banner = iQ("<div>")
       .text(notificationText)
       .addClass("banner")
       .appendTo("body");
     let onFadeOut = function () {
       banner.remove();
     };
     let onFadeIn = function () {
       setTimeout(function () {
         banner.animate({opacity: 0}, {duration: 1500, complete: onFadeOut});
       }, 5000);
     };
     banner.animate({opacity: 0.7}, {duration: 1500, complete: onFadeIn});
   }
 };
 // ----------
 UI.init();