gecko/browser/base/content/tabbrowser.xml

<?xml version="1.0"?>

<!-- ***** BEGIN LICENSE BLOCK *****
   - Version: MPL 1.1/GPL 2.0/LGPL 2.1
   -
   - The contents of this file are subject to the Mozilla Public License Version
   - 1.1 (the "License"); you may not use this file except in compliance with
   - the License. You may obtain a copy of the License at
   - http://www.mozilla.org/MPL/
   -
   - Software distributed under the License is distributed on an "AS IS" basis,
   - WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
   - for the specific language governing rights and limitations under the
   - License.
   -
   - The Original Code is this file as it was released on March 28, 2001.
   -
   - The Initial Developer of the Original Code is
   - David Hyatt.
   - Portions created by the Initial Developer are Copyright (C) 2001
   - the Initial Developer. All Rights Reserved.
   -
   - Contributor(s):
   -   David Hyatt <hyatt@netscape.com> (Original Author of <tabbrowser>)
   -   Mike Connor <mconnor@steelgryphon.com>
   -   Peter Parente <parente@cs.unc.edu>
   -   Giorgio Maone <g.maone@informaction.com>
   -   Asaf Romano <mozilla.mano@sent.com>
   -   Seth Spitzer <sspitzer@mozilla.org>
   -   Simon Bünzli <zeniko@gmail.com>
   -   Michael Ventnor <ventnor.bugzilla@yahoo.com.au>
   -   Mark Pilgrim <pilgrim@gmail.com>
   -   Dão Gottwald <dao@mozilla.com>
   -   Paul O’Shannessy <paul@oshannessy.com>
   -   Rob Arnold <tellrob@gmail.com>
   -
   - Alternatively, the contents of this file may be used under the terms of
   - either the GNU General Public License Version 2 or later (the "GPL"), or
   - the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
   - in which case the provisions of the GPL or the LGPL are applicable instead
   - of those above. If you wish to allow use of your version of this file only
   - under the terms of either the GPL or the LGPL, and not to allow others to
   - use your version of this file under the terms of the MPL, indicate your
   - decision by deleting the provisions above and replace them with the notice
   - and other provisions required by the GPL or the LGPL. If you do not delete
   - the provisions above, a recipient may use your version of this file under
   - the terms of any one of the MPL, the GPL or the LGPL.
   -
   - ***** END LICENSE BLOCK ***** -->

<!DOCTYPE bindings [
<!ENTITY % tabBrowserDTD SYSTEM "chrome://browser/locale/tabbrowser.dtd" >
%tabBrowserDTD;
]>

<bindings id="tabBrowserBindings"
          xmlns="http://www.mozilla.org/xbl"
          xmlns:xul="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul"
          xmlns:xbl="http://www.mozilla.org/xbl">

  <binding id="tabbrowser">
    <resources>
      <stylesheet src="chrome://browser/content/tabbrowser.css"/>
    </resources>

    <content>
      <xul:stringbundle anonid="tbstringbundle" src="chrome://browser/locale/tabbrowser.properties"/>
      <xul:tabbox anonid="tabbox" class="tabbrowser-tabbox"
                  flex="1" eventnode="document" xbl:inherits="handleCtrlPageUpDown"
                  onselect="if (event.target.localName == 'tabpanels') this.parentNode.updateCurrentBrowser();">
        <xul:tabpanels flex="1" class="plain" selectedIndex="0" anonid="panelcontainer">
          <xul:notificationbox flex="1">
            <xul:browser flex="1" type="content-primary" message="true" disablehistory="true"
                         xbl:inherits="tooltip=contenttooltip,contextmenu=contentcontextmenu,autocompletepopup"/>
          </xul:notificationbox>
        </xul:tabpanels>
      </xul:tabbox>
      <children/>
    </content>
    <implementation implements="nsIDOMEventListener">

      <property name="tabContextMenu" readonly="true"
                onget="return this.tabContainer.contextMenu;"/>

      <field name="tabContainer" readonly="true">
        document.getElementById(this.getAttribute("tabcontainer"));
      </field>
      <field name="tabs" readonly="true">
        this.tabContainer.childNodes;
      </field>
      <property name="visibleTabs" readonly="true">
        <getter><![CDATA[
          return Array.filter(this.tabs, function(tab) {
            return !tab.hidden && this._removingTabs.indexOf(tab) == -1;
          }, this);
        ]]></getter>
      </property>
      <field name="mURIFixup" readonly="true">
        Components.classes["@mozilla.org/docshell/urifixup;1"]
                  .getService(Components.interfaces.nsIURIFixup);
      </field>
      <field name="mFaviconService" readonly="true">
        Components.classes["@mozilla.org/browser/favicon-service;1"]
                  .getService(Components.interfaces.nsIFaviconService);
      </field>
      <field name="mBrowserHistory" readonly="true">
        Components.classes["@mozilla.org/browser/nav-history-service;1"]
                  .getService(Components.interfaces.nsIBrowserHistory);
      </field>
      <field name="mTabBox" readonly="true">
        document.getAnonymousElementByAttribute(this, "anonid", "tabbox");
      </field>
      <field name="mPanelContainer" readonly="true">
        document.getAnonymousElementByAttribute(this, "anonid", "panelcontainer");
      </field>
      <field name="mStringBundle">
        document.getAnonymousElementByAttribute(this, "anonid", "tbstringbundle");
      </field>
      <field name="mCurrentTab">
        null
      </field>
      <field name="_lastRelatedTab">
        null
      </field>
      <field name="mCurrentBrowser">
        null
      </field>
      <field name="mProgressListeners">
        []
      </field>
      <field name="mTabsProgressListeners">
        []
      </field>
      <field name="mTabListeners">
        new Array()
      </field>
      <field name="mTabFilters">
        new Array()
      </field>
      <field name="mTabbedMode">
        false
      </field>
      <field name="mIsBusy">
        false
      </field>
      <field name="arrowKeysShouldWrap" readonly="true">
#ifdef XP_MACOSX
        true
#else
        false
#endif
      </field>
      <field name="mAddProgressListenerWasCalled">
        false
      </field>
      <field name="_browsers">
        null
      </field>

      <field name="_autoScrollPopup">
        null
      </field>

      <field name="_previewMode">
        false
      </field>

      <property name="_numPinnedTabs" readonly="true">
        <getter><![CDATA[
          for (var i = 0; i < this.tabs.length; i++) {
            if (!this.tabs[i].pinned)
              break;
          }
          return i;
        ]]></getter>
      </property>

      <method name="pinTab">
        <parameter name="aTab"/>
        <body><![CDATA[
          if (aTab.pinned)
            return;

          this.moveTabTo(aTab, this._numPinnedTabs);
          aTab.setAttribute("pinned", "true");
          this.tabContainer._positionPinnedTabs();
          this.tabContainer.adjustTabstrip();
        ]]></body>
      </method>

      <method name="unpinTab">
        <parameter name="aTab"/>
        <body><![CDATA[
          if (!aTab.pinned)
            return;

          this.moveTabTo(aTab, this._numPinnedTabs - 1);
          aTab.setAttribute("fadein", "true");
          aTab.removeAttribute("pinned");
          aTab.style.MozMarginStart = "";
          this.tabContainer._positionPinnedTabs();
          this.tabContainer.adjustTabstrip();
        ]]></body>
      </method>

      <method name="previewTab">
        <parameter name="aTab"/>
        <parameter name="aCallback"/>
        <body>
          <![CDATA[
            let currentTab = this.selectedTab;
            try {
              // Suppress focus, ownership and selected tab changes
              this._previewMode = true;
              this.selectedTab = aTab;
              aCallback();
            } finally {
              this.selectedTab = currentTab;
              this._previewMode = false;
            }
          ]]>
        </body>
      </method>

      <method name="getBrowserAtIndex">
        <parameter name="aIndex"/>
        <body>
          <![CDATA[
            return this.browsers[aIndex];
          ]]>
        </body>
      </method>

      <method name="getBrowserIndexForDocument">
        <parameter name="aDocument"/>
        <body>
          <![CDATA[
            var tab = this._getTabForContentWindow(aDocument.defaultView);
            return tab ? tab._tPos : -1;
          ]]>
        </body>
      </method>

      <method name="getBrowserForDocument">
        <parameter name="aDocument"/>
        <body>
          <![CDATA[
            var tab = this._getTabForContentWindow(aDocument.defaultView);
            return tab ? tab.linkedBrowser : null;
          ]]>
        </body>
      </method>

      <method name="_getTabForContentWindow">
        <parameter name="aWindow"/>
        <body>
        <![CDATA[
          for (let i = 0; i < this.browsers.length; i++) {
            if (this.browsers[i].contentWindow == aWindow)
              return this.tabs[i];
          }
          return null;
        ]]>
        </body>
      </method>

      <method name="getNotificationBox">
        <parameter name="aBrowser"/>
        <body>
          <![CDATA[
            return (aBrowser || this.mCurrentBrowser).parentNode;
          ]]>
        </body>
      </method>

      <method name="_callProgressListeners">
        <parameter name="aBrowser"/>
        <parameter name="aMethod"/>
        <parameter name="aArguments"/>
        <parameter name="aCallGlobalListeners"/>
        <parameter name="aCallTabsListeners"/>
        <body><![CDATA[
          var rv = true;

          if (!aBrowser)
            aBrowser = this.mCurrentBrowser;

          if (aCallGlobalListeners != false &&
              aBrowser == this.mCurrentBrowser) {
            this.mProgressListeners.forEach(function (p) {
              if (aMethod in p) {
                try {
                  if (!p[aMethod].apply(p, aArguments))
                    rv = false;
                } catch (e) {
                  // don't inhibit other listeners
                  Components.utils.reportError(e);
                }
              }
            });
          }

          if (aCallTabsListeners != false) {
            aArguments.unshift(aBrowser);

            this.mTabsProgressListeners.forEach(function (p) {
              if (aMethod in p) {
                try {
                  if (!p[aMethod].apply(p, aArguments))
                    rv = false;
                } catch (e) {
                  // don't inhibit other listeners
                  Components.utils.reportError(e);
                }
              }
            });
          }

          return rv;
        ]]></body>
      </method>

      <!-- A web progress listener object definition for a given tab. -->
      <method name="mTabProgressListener">
        <parameter name="aTab"/>
        <parameter name="aBrowser"/>
        <parameter name="aStartsBlank"/>
        <body>
        <![CDATA[
          return ({
            mTabBrowser: this,
            mTab: aTab,
            mBrowser: aBrowser,
            mBlank: aStartsBlank,

            // cache flags for correct status bar update after tab switching
            mStateFlags: 0,
            mStatus: 0,
            mMessage: "",
            mTotalProgress: 0,

            // count of open requests (should always be 0 or 1)
            mRequestCount: 0,

            destroy: function () {
              this._cancelStalledTimer();
              this.mTab.removeAttribute("stalled");
              delete this.mTab;
              delete this.mBrowser;
              delete this.mTabBrowser;
            },

            _callProgressListeners: function () {
              Array.unshift(arguments, this.mBrowser);
              return this.mTabBrowser._callProgressListeners.apply(this.mTabBrowser, arguments);
            },

            onProgressChange: function (aWebProgress, aRequest,
                                        aCurSelfProgress, aMaxSelfProgress,
                                        aCurTotalProgress, aMaxTotalProgress) {
              this.mTotalProgress = aMaxTotalProgress ? aCurTotalProgress / aMaxTotalProgress : 0;

              if (this.mBlank)
                return;

              if (this.mTotalProgress) {
                const STATES = 8;
                let state = Math.ceil(STATES * this.mTotalProgress);
                if (state != this.mTab.getAttribute("progress")) {
                  this.mTab.setAttribute("progress", state);
                  this.mTab.removeAttribute("stalled");
                  this._startStalledTimer();
                }
              }

              this._callProgressListeners("onProgressChange",
                                          [aWebProgress, aRequest,
                                           aCurSelfProgress, aMaxSelfProgress,
                                           aCurTotalProgress, aMaxTotalProgress]);
            },

            onProgressChange64: function (aWebProgress, aRequest,
                                          aCurSelfProgress, aMaxSelfProgress,
                                          aCurTotalProgress, aMaxTotalProgress) {
              return this.onProgressChange(aWebProgress, aRequest,
                aCurSelfProgress, aMaxSelfProgress, aCurTotalProgress,
                aMaxTotalProgress);
            },

            onStateChange: function (aWebProgress, aRequest, aStateFlags, aStatus) {
              if (!aRequest)
                return;

              var oldBlank = this.mBlank;

              const nsIWebProgressListener = Components.interfaces.nsIWebProgressListener;
              const nsIChannel = Components.interfaces.nsIChannel;

              if (aStateFlags & nsIWebProgressListener.STATE_START) {
                this.mRequestCount++;
              }
              else if (aStateFlags & nsIWebProgressListener.STATE_STOP) {
                const NS_ERROR_UNKNOWN_HOST = 2152398878;
                if (--this.mRequestCount > 0 && aStatus == NS_ERROR_UNKNOWN_HOST) {
                  // to prevent bug 235825: wait for the request handled
                  // by the automatic keyword resolver
                  return;
                }
                // since we (try to) only handle STATE_STOP of the last request,
                // the count of open requests should now be 0
                this.mRequestCount = 0;
              }

              if (aStateFlags & nsIWebProgressListener.STATE_START &&
                  aStateFlags & nsIWebProgressListener.STATE_IS_NETWORK) {
                // It's okay to clear what the user typed when we start
                // loading a document. If the user types, this counter gets
                // set to zero, if the document load ends without an
                // onLocationChange, this counter gets decremented
                // (so we keep it while switching tabs after failed loads)
                // We need to add 2 because loadURIWithFlags may have
                // cancelled a pending load which would have cleared
                // its anchor scroll detection temporary increment.
                if (aWebProgress.DOMWindow == this.mBrowser.contentWindow)
                  this.mBrowser.userTypedClear += 2;

                if (!this.mBlank) {
                  if (!(aStateFlags & nsIWebProgressListener.STATE_RESTORING)) {
                    this.mTab.setAttribute("busy", "true");
                    this._startStalledTimer();
                    this.mTabBrowser.updateIcon(this.mTab);
                    this.mTabBrowser.setTabTitleLoading(this.mTab);
                  }

                  if (this.mTabBrowser.mCurrentTab == this.mTab)
                    this.mTabBrowser.mIsBusy = true;
                }
              }
              else if (aStateFlags & nsIWebProgressListener.STATE_STOP &&
                       aStateFlags & nsIWebProgressListener.STATE_IS_NETWORK) {
                if (aWebProgress.DOMWindow == this.mBrowser.contentWindow) {
                  // The document is done loading, we no longer want the
                  // value cleared.
                  if (this.mBrowser.userTypedClear > 1)
                    this.mBrowser.userTypedClear -= 2;
                  else if (this.mBrowser.userTypedClear > 0)
                    this.mBrowser.userTypedClear--;

                  if (!this.mBrowser.mIconURL)
                    this.mTabBrowser.useDefaultIcon(this.mTab);
                }

                if (this.mBlank)
                  this.mBlank = false;

                this.mTab.removeAttribute("busy");
                this.mTab.removeAttribute("progress");
                this.mTab.removeAttribute("stalled");
                this._cancelStalledTimer();
                this.mTabBrowser.updateIcon(this.mTab);

                var location = aRequest.QueryInterface(nsIChannel).URI;

                // For keyword URIs clear the user typed value since they will be changed into real URIs
                if (location.scheme == "keyword")
                  this.mBrowser.userTypedValue = null;

                if (this.mTab.label == this.mTabBrowser.mStringBundle.getString("tabs.loading"))
                  this.mTabBrowser.setTabTitle(this.mTab);

                if (this.mTabBrowser.mCurrentTab == this.mTab)
                  this.mTabBrowser.mIsBusy = false;
              }

              if (oldBlank) {
                this._callProgressListeners("onUpdateCurrentBrowser",
                                            [aStateFlags, aStatus, "", 0],
                                            true, false);
              } else {
                this._callProgressListeners("onStateChange",
                                            [aWebProgress, aRequest, aStateFlags, aStatus],
                                            true, false);
              }

              this._callProgressListeners("onStateChange",
                                          [aWebProgress, aRequest, aStateFlags, aStatus],
                                          false);

              if (aStateFlags & (nsIWebProgressListener.STATE_START |
                                 nsIWebProgressListener.STATE_STOP)) {
                // reset cached temporary values at beginning and end
                this.mMessage = "";
                this.mTotalProgress = 0;
              }
              this.mStateFlags = aStateFlags;
              this.mStatus = aStatus;
            },

            onLocationChange: function (aWebProgress, aRequest, aLocation) {
              // OnLocationChange is called for both the top-level content
              // and the subframes.
              let topLevel = aWebProgress.DOMWindow == this.mBrowser.contentWindow;

              if (topLevel) {
                // The document loaded correctly, clear the value if we should
                if (this.mBrowser.userTypedClear > 0)
                  this.mBrowser.userTypedValue = null;

                // Clear out the missing plugins list since it's related to the
                // previous location.
                this.mBrowser.missingPlugins = null;

                // Don't clear the favicon if this onLocationChange was
                // triggered by a pushState or a replaceState.  See bug 550565.
                if (aWebProgress.isLoadingDocument &&
                    !(this.mBrowser.docShell.loadType & Ci.nsIDocShell.LOAD_CMD_PUSHSTATE))
                  this.mBrowser.mIconURL = null;

                let browserHistory = this.mTabBrowser.mBrowserHistory;
                if (this.mBrowser.registeredOpenURI) {
                  browserHistory.unregisterOpenPage(this.mBrowser.registeredOpenURI);
                  delete this.mBrowser.registeredOpenURI;
                }
                browserHistory.registerOpenPage(aLocation);
                this.mBrowser.registeredOpenURI = aLocation;
              }

              if (!this.mBlank) {
                this._callProgressListeners("onLocationChange",
                                            [aWebProgress, aRequest, aLocation]);
              }

              if (topLevel)
                this.mBrowser.lastURI = aLocation;
            },

            onStatusChange: function (aWebProgress, aRequest, aStatus, aMessage) {
              if (this.mBlank)
                return;

              this._callProgressListeners("onStatusChange",
                                          [aWebProgress, aRequest, aStatus, aMessage]);

              this.mMessage = aMessage;
            },

            onSecurityChange: function (aWebProgress, aRequest, aState) {
              this._callProgressListeners("onSecurityChange",
                                          [aWebProgress, aRequest, aState]);
            },

            onRefreshAttempted: function (aWebProgress, aURI, aDelay, aSameURI) {
              return this._callProgressListeners("onRefreshAttempted",
                                                 [aWebProgress, aURI, aDelay, aSameURI]);
            },

            QueryInterface: function (aIID) {
              if (aIID.equals(Components.interfaces.nsIWebProgressListener) ||
                  aIID.equals(Components.interfaces.nsIWebProgressListener2) ||
                  aIID.equals(Components.interfaces.nsISupportsWeakReference) ||
                  aIID.equals(Components.interfaces.nsISupports))
                return this;
              throw Components.results.NS_NOINTERFACE;
            },

            _startStalledTimer: function () {
              this._cancelStalledTimer();
              this._stalledTimer = setTimeout(function (self) { 
                self.mTab.setAttribute("stalled", "true");
              }, 700, this);
            },

            _cancelStalledTimer: function () {
              if (this._stalledTimer) {
                clearTimeout(this._stalledTimer);
                this._stalledTimer = 0;
              }
            }
          });
        ]]>
        </body>
      </method>

      <method name="setIcon">
        <parameter name="aTab"/>
        <parameter name="aURI"/>
        <body>
          <![CDATA[
            var browser = this.getBrowserForTab(aTab);
            browser.mIconURL = aURI instanceof Ci.nsIURI ? aURI.spec : aURI;

            if (aURI && this.mFaviconService) {
              if (!(aURI instanceof Ci.nsIURI))
                aURI = makeURI(aURI);
              this.mFaviconService.setAndLoadFaviconForPage(browser.currentURI,
                                                            aURI, false);
            }

            this.updateIcon(aTab);

            this._callProgressListeners(browser, "onLinkIconAvailable", [browser.mIconURL]);
          ]]>
        </body>
      </method>

      <method name="getIcon">
        <parameter name="aTab"/>
        <body>
          <![CDATA[
            let browser = aTab ? this.getBrowserForTab(aTab) : this.selectedBrowser;
            return browser.mIconURL;
          ]]>
        </body>
      </method>

      <method name="updateIcon">
        <parameter name="aTab"/>
        <body>
          <![CDATA[
            var browser = this.getBrowserForTab(aTab);
            if (!aTab.hasAttribute("busy") && browser.mIconURL)
              aTab.setAttribute("image", browser.mIconURL);
            else
              aTab.removeAttribute("image");
            this._tabAttrModified(aTab);
          ]]>
        </body>
      </method>

      <method name="shouldLoadFavIcon">
        <parameter name="aURI"/>
        <body>
          <![CDATA[
            return (aURI &&
                    Services.prefs.getBoolPref("browser.chrome.site_icons") &&
                    Services.prefs.getBoolPref("browser.chrome.favicons") &&
                    ("schemeIs" in aURI) && (aURI.schemeIs("http") || aURI.schemeIs("https")));
          ]]>
        </body>
      </method>

      <method name="useDefaultIcon">
        <parameter name="aTab"/>
        <body>
          <![CDATA[
            var browser = this.getBrowserForTab(aTab);
            var docURIObject = browser.contentDocument.documentURIObject; 
            if (browser.contentDocument instanceof ImageDocument) {
              if (Services.prefs.getBoolPref("browser.chrome.site_icons")) {
                try {
                  let sz = Services.prefs.getIntPref("browser.chrome.image_icons.max_size");
                  if (!sz)
                    return;

                  var req = browser.contentDocument.imageRequest;
                  if (!req || !req.image ||
                      req.image.width > sz ||
                      req.image.height > sz)
                    return;

                  this.setIcon(aTab, browser.currentURI);
                } catch (e) { }
              }
            }
            // Use documentURIObject in the check for shouldLoadFavIcon so that we
            // do the right thing with about:-style error pages.  Bug 453442
            else if (this.shouldLoadFavIcon(docURIObject)) {
              var url = docURIObject.prePath + "/favicon.ico";
              if (!this.isFailedIcon(url))
                this.setIcon(aTab, url);
            }
          ]]>
        </body>
      </method>

      <method name="isFailedIcon">
        <parameter name="aURI"/>
        <body>
          <![CDATA[
            if (this.mFaviconService) {
              if (!(aURI instanceof Ci.nsIURI))
                aURI = makeURI(aURI);
              return this.mFaviconService.isFailedFavicon(aURI);
            }
            return null;
          ]]>
        </body>
      </method>

      <method name="getWindowTitleForBrowser">
        <parameter name="aBrowser"/>
        <body>
          <![CDATA[
            var newTitle = "";
            var docTitle;
            var docElement = this.ownerDocument.documentElement;
            var sep = docElement.getAttribute("titlemenuseparator");

            if (aBrowser.docShell.contentViewer)
              docTitle = aBrowser.contentTitle;

            if (!docTitle)
              docTitle = docElement.getAttribute("titledefault");

            var modifier = docElement.getAttribute("titlemodifier");
            if (docTitle) {
              newTitle += docElement.getAttribute("titlepreface");
              newTitle += docTitle;
              if (modifier)
                newTitle += sep;
            }
            newTitle += modifier;

            // If location bar is hidden and the URL type supports a host,
            // add the scheme and host to the title to prevent spoofing.
            // XXX https://bugzilla.mozilla.org/show_bug.cgi?id=22183#c239
            try {
              if (docElement.getAttribute("chromehidden").indexOf("location") != -1) {
                var uri = this.mURIFixup.createExposableURI(
                            aBrowser.currentURI);
                if (uri.scheme == "about")
                  newTitle = uri.spec + sep + newTitle;
                else
                  newTitle = uri.prePath + sep + newTitle;
              }
            } catch (e) {}

            return newTitle;
          ]]>
        </body>
      </method>

      <method name="updateTitlebar">
        <body>
          <![CDATA[
            if (window.TabView && TabView.isVisible()) {
              // ToDo: this will be removed when we gain ability to draw to the menu bar.
              // Bug 586175
              this.ownerDocument.title = TabView.windowTitle;
            } else {
              this.ownerDocument.title = this.getWindowTitleForBrowser(this.mCurrentBrowser);
            }
          ]]>
        </body>
      </method>

      <method name="updateCurrentBrowser">
        <parameter name="aForceUpdate"/>
        <body>
          <![CDATA[
            var newBrowser = this.getBrowserAtIndex(this.tabContainer.selectedIndex);
            if (this.mCurrentBrowser == newBrowser && !aForceUpdate)
              return;

            var oldTab = this.mCurrentTab;

            // Preview mode should not reset the owner
            if (!this._previewMode && oldTab != this.selectedTab)
              oldTab.owner = null;

            this._lastRelatedTab = null;

            var oldBrowser = this.mCurrentBrowser;
            if (oldBrowser) {
              oldBrowser.setAttribute("type", "content-targetable");
              oldBrowser.docShell.isActive = false;
            }

            var updatePageReport = false;
            if (!oldBrowser ||
                (oldBrowser.pageReport && !newBrowser.pageReport) ||
                (!oldBrowser.pageReport && newBrowser.pageReport))
              updatePageReport = true;

            newBrowser.setAttribute("type", "content-primary");
            newBrowser.docShell.isActive = true;
            this.mCurrentBrowser = newBrowser;
            this.mCurrentTab = this.selectedTab;
            this.showTab(this.mCurrentTab);

            if (updatePageReport)
              this.mCurrentBrowser.updatePageReport();

            // Update the URL bar.
            var loc = this.mCurrentBrowser.currentURI;

            var webProgress = this.mCurrentBrowser.webProgress;
            var securityUI = this.mCurrentBrowser.securityUI;

            this._callProgressListeners(null, "onLocationChange",
                                        [webProgress, null, loc], true, false);

            if (securityUI) {
              this._callProgressListeners(null, "onSecurityChange",
                                          [webProgress, null, securityUI.state], true, false);
            }

            var listener = this.mTabListeners[this.tabContainer.selectedIndex] || null;
            if (listener && listener.mStateFlags) {
              this._callProgressListeners(null, "onUpdateCurrentBrowser",
                                          [listener.mStateFlags, listener.mStatus,
                                           listener.mMessage, listener.mTotalProgress],
                                          true, false);
            }

            // Don't switch the fast find or update the titlebar (bug 540248) - this tab switch is temporary
            if (!this._previewMode) {
              this._fastFind.setDocShell(this.mCurrentBrowser.docShell);

              this.updateTitlebar();
            }

            // If the new tab is busy, and our current state is not busy, then
            // we need to fire a start to all progress listeners.
            const nsIWebProgressListener = Components.interfaces.nsIWebProgressListener;
            if (this.mCurrentTab.hasAttribute("busy") && !this.mIsBusy) {
              this.mIsBusy = true;
              this._callProgressListeners(null, "onStateChange",
                                          [webProgress, null,
                                           nsIWebProgressListener.STATE_START |
                                           nsIWebProgressListener.STATE_IS_NETWORK, 0],
                                          true, false);
            }

            // If the new tab is not busy, and our current state is busy, then
            // we need to fire a stop to all progress listeners.
            if (!this.mCurrentTab.hasAttribute("busy") && this.mIsBusy) {
              this.mIsBusy = false;
              this._callProgressListeners(null, "onStateChange",
                                          [webProgress, null,
                                           nsIWebProgressListener.STATE_STOP |
                                           nsIWebProgressListener.STATE_IS_NETWORK, 0],
                                          true, false);
            }

            // TabSelect events are suppressed during preview mode to avoid confusing extensions and other bits of code
            // that might rely upon the other changes suppressed.
            // Focus is suppressed in the event that the main browser window is minimized - focusing a tab would restore the window
            if (!this._previewMode) {
              // We've selected the new tab, so go ahead and notify listeners.
              var event = document.createEvent("Events");
              event.initEvent("TabSelect", true, false);
              this.mCurrentTab.dispatchEvent(event);

              this._tabAttrModified(oldTab);
              this._tabAttrModified(this.mCurrentTab);

              // Change focus to the new browser unless the findbar is focused.
              if (!gFindBarInitialized ||
                  gFindBar.hidden ||
                  gFindBar.getElement("findbar-textbox").getAttribute("focused") != "true") {

                var fm = Components.classes["@mozilla.org/focus-manager;1"].
                           getService(Components.interfaces.nsIFocusManager);
                var newFocusedElement = fm.getFocusedElementForWindow(window.content, true, {});

                // for anchors, use FLAG_SHOWRING so that it is clear what link was
                // last clicked when switching back to that tab
                var focusFlags = fm.FLAG_NOSCROLL;
                if (newFocusedElement &&
                    (newFocusedElement instanceof HTMLAnchorElement ||
                     newFocusedElement.getAttributeNS("http://www.w3.org/1999/xlink", "type") == "simple"))
                  focusFlags |= fm.FLAG_SHOWRING;
                fm.setFocus(newBrowser, focusFlags);
              }
            }
          ]]>
        </body>
      </method>

      <method name="_tabAttrModified">
        <parameter name="aTab"/>
        <body><![CDATA[
          // This event should be dispatched when any of these attributes change:
          // label, crop, busy, image, selected
          var event = document.createEvent("Events");
          event.initEvent("TabAttrModified", true, false);
          aTab.dispatchEvent(event);
        ]]></body>
      </method>

      <method name="setTabTitleLoading">
        <parameter name="aTab"/>
        <body>
          <![CDATA[
            aTab.label = this.mStringBundle.getString("tabs.loading");
            aTab.setAttribute("crop", "end");
            this._tabAttrModified(aTab);
          ]]>
        </body>
      </method>

      <method name="setTabTitle">
        <parameter name="aTab"/>
        <body>
          <![CDATA[
            var browser = this.getBrowserForTab(aTab);
            var crop = "end";
            var title = browser.contentTitle;

            if (!title) {
              if (browser.currentURI.spec) {
                try {
                  title = this.mURIFixup.createExposableURI(browser.currentURI).spec;
                } catch(ex) {
                  title = browser.currentURI.spec;
                }
              }

              if (title && title != "about:blank") {
                // At this point, we now have a URI.
                // Let's try to unescape it using a character set
                // in case the URI is not ASCII.
                try {
                  var characterSet = browser.contentDocument.characterSet;
                  const textToSubURI = Components.classes["@mozilla.org/intl/texttosuburi;1"]
                                                 .getService(Components.interfaces.nsITextToSubURI);
                  title = textToSubURI.unEscapeNonAsciiURI(characterSet, title);
                } catch(ex) { /* Do nothing. */ }

                crop = "center";

              } else // Still no title?  Fall back to our untitled string.
                title = this.mStringBundle.getString("tabs.emptyTabTitle");
            }

            aTab.label = title;
            aTab.setAttribute("crop", crop);
            this._tabAttrModified(aTab);
          ]]>
        </body>
      </method>

      <method name="enterTabbedMode">
        <body>
          <![CDATA[
            if (this.mTabbedMode)
              return;

            this.mTabbedMode = true; // Welcome to multi-tabbed mode.

            if (XULBrowserWindow.isBusy) {
              this.mCurrentTab.setAttribute("busy", "true");
              this.mIsBusy = true;
              this.setTabTitleLoading(this.mCurrentTab);
              this.updateIcon(this.mCurrentTab);
            } else {
              this.setIcon(this.mCurrentTab, this.mCurrentBrowser.mIconURL);
            }

            var filter;
            if (this.mTabFilters.length > 0) {
              // Use the filter hooked up in our addProgressListener
              filter = this.mTabFilters[0];
            } else {
              // create a filter and hook it up to our first browser
              filter = Components.classes["@mozilla.org/appshell/component/browser-status-filter;1"]
                                 .createInstance(Components.interfaces.nsIWebProgress);
              this.mTabFilters[0] = filter;
              this.mCurrentBrowser.webProgress.addProgressListener(filter, Components.interfaces.nsIWebProgress.NOTIFY_ALL);
            }

            // Remove all our progress listeners from the active browser's filter.
            this.mProgressListeners.forEach(filter.removeProgressListener, filter);

            // Wire up a progress listener to our filter.
            const listener = this.mTabProgressListener(this.mCurrentTab,
                                                       this.mCurrentBrowser,
                                                       false);
            filter.addProgressListener(listener, Components.interfaces.nsIWebProgress.NOTIFY_ALL);
            this.mTabListeners[0] = listener;
          ]]>
        </body>
      </method>

      <method name="loadOneTab">
        <parameter name="aURI"/>
        <parameter name="aReferrerURI"/>
        <parameter name="aCharset"/>
        <parameter name="aPostData"/>
        <parameter name="aLoadInBackground"/>
        <parameter name="aAllowThirdPartyFixup"/>
        <body>
          <![CDATA[
            var aFromExternal;
            var aRelatedToCurrent;
            if (arguments.length == 2 &&
                typeof arguments[1] == "object" &&
                !(arguments[1] instanceof Ci.nsIURI)) {
              let params = arguments[1];
              aReferrerURI          = params.referrerURI;
              aCharset              = params.charset;
              aPostData             = params.postData;
              aLoadInBackground     = params.inBackground;
              aAllowThirdPartyFixup = params.allowThirdPartyFixup;
              aFromExternal         = params.fromExternal;
              aRelatedToCurrent     = params.relatedToCurrent;
            }

            var bgLoad = (aLoadInBackground != null) ? aLoadInBackground :
                         Services.prefs.getBoolPref("browser.tabs.loadInBackground");
            var owner = bgLoad ? null : this.selectedTab;
            var tab = this.addTab(aURI, {
                                  referrerURI: aReferrerURI,
                                  charset: aCharset,
                                  postData: aPostData,
                                  ownerTab: owner,
                                  allowThirdPartyFixup: aAllowThirdPartyFixup,
                                  fromExternal: aFromExternal,
                                  relatedToCurrent: aRelatedToCurrent});
            if (!bgLoad)
              this.selectedTab = tab;

            return tab;
         ]]>
        </body>
      </method>

      <method name="loadTabs">
        <parameter name="aURIs"/>
        <parameter name="aLoadInBackground"/>
        <parameter name="aReplace"/>
        <body><![CDATA[
          if (!aURIs.length)
            return;

          // The tab selected after this new tab is closed (i.e. the new tab's
          // "owner") is the next adjacent tab (i.e. not the previously viewed tab)
          // when several urls are opened here (i.e. closing the first should select
          // the next of many URLs opened) or if the pref to have UI links opened in
          // the background is set (i.e. the link is not being opened modally)
          //
          // i.e.
          //    Number of URLs    Load UI Links in BG       Focus Last Viewed?
          //    == 1              false                     YES
          //    == 1              true                      NO
          //    > 1               false/true                NO
          var multiple = aURIs.length > 1;
          var owner = multiple || aLoadInBackground ? null : this.selectedTab;
          var firstTabAdded = null;

          if (aReplace) {
            try {
              this.loadURI(aURIs[0], null, null);
            } catch (e) {
              // Ignore failure in case a URI is wrong, so we can continue
              // opening the next ones.
            }
          }
          else
            firstTabAdded = this.addTab(aURIs[0], {ownerTab: owner, skipAnimation: multiple});

          var tabNum = this.tabContainer.selectedIndex;
          for (let i = 1; i < aURIs.length; ++i) {
            let tab = this.addTab(aURIs[i], {skipAnimation: true});
            if (aReplace)
              this.moveTabTo(tab, ++tabNum);
          }

          if (!aLoadInBackground) {
            if (firstTabAdded) {
              // .selectedTab setter focuses the content area
              this.selectedTab = firstTabAdded;
            }
            else
              window.content.focus();
          }
        ]]></body>
      </method>

      <method name="addTab">
        <parameter name="aURI"/>
        <parameter name="aReferrerURI"/>
        <parameter name="aCharset"/>
        <parameter name="aPostData"/>
        <parameter name="aOwner"/>
        <parameter name="aAllowThirdPartyFixup"/>
        <body>
          <![CDATA[
            var aFromExternal;
            var aRelatedToCurrent;
            var aSkipAnimation;
            if (arguments.length == 2 &&
                typeof arguments[1] == "object" &&
                !(arguments[1] instanceof Ci.nsIURI)) {
              let params = arguments[1];
              aReferrerURI          = params.referrerURI;
              aCharset              = params.charset;
              aPostData             = params.postData;
              aOwner                = params.ownerTab;
              aAllowThirdPartyFixup = params.allowThirdPartyFixup;
              aFromExternal         = params.fromExternal;
              aRelatedToCurrent     = params.relatedToCurrent;
              aSkipAnimation        = params.skipAnimation;
            }

            this._browsers = null; // invalidate cache

            this.enterTabbedMode();

            // if we're adding tabs, we're past interrupt mode, ditch the owner
            if (this.mCurrentTab.owner)
              this.mCurrentTab.owner = null;

            var t = document.createElementNS(
              "http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul",
                                             "tab");

            var blank = !aURI || (aURI == "about:blank");

            if (blank)
              t.setAttribute("label", this.mStringBundle.getString("tabs.emptyTabTitle"));
            else
              t.setAttribute("label", aURI);

            t.setAttribute("crop", "end");
            t.setAttribute("validate", "never");
            t.setAttribute("onerror", "this.removeAttribute('image');");
            t.className = "tabbrowser-tab";

            // When overflowing, new tabs are scrolled into view smoothly, which
            // doesn't go well together with the width transition. So we skip the
            // transition in that case.
            if (aSkipAnimation ||
                this.tabContainer.getAttribute("overflow") == "true" ||
                !Services.prefs.getBoolPref("browser.tabs.animate")) {
              t.setAttribute("fadein", "true");
              setTimeout(function (tabContainer) {
                tabContainer._handleNewTab(t);
              }, 0, this.tabContainer);
            } else {
              setTimeout(function (tabContainer) {
                if (t.pinned)
                  tabContainer._handleNewTab(t);
                else
                  t.setAttribute("fadein", "true");
              }, 0, this.tabContainer);
            }

            this.tabContainer.appendChild(t);

            if (this.tabContainer.mTabstrip._isRTLScrollbox) {
              /* In RTL UI, the tab is visually added to the left side of the
               * tabstrip. This means the tabstip has to be scrolled back in
               * order to make sure the same set of tabs is visible before and
               * after the new tab is added.  See bug 508816. */

              this.tabContainer.mTabstrip.scrollByPixels(t.clientWidth);
            }

            // invalidate cache, because tabContainer is about to change
            this._browsers = null;

            // If this new tab is owned by another, assert that relationship
            if (aOwner)
              t.owner = aOwner;

            var b = document.createElementNS(
              "http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul",
                                             "browser");
            b.setAttribute("type", "content-targetable");
            b.setAttribute("message", "true");
            b.setAttribute("contextmenu", this.getAttribute("contentcontextmenu"));
            b.setAttribute("tooltip", this.getAttribute("contenttooltip"));
            if (this.hasAttribute("autocompletepopup"))
              b.setAttribute("autocompletepopup", this.getAttribute("autocompletepopup"));
            b.setAttribute("autoscrollpopup", this._autoScrollPopup.id);

            // Add the Message and the Browser to the box
            var notificationbox = document.createElementNS(
                                    "http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul",
                                    "notificationbox");
            notificationbox.setAttribute("flex", "1");
            notificationbox.appendChild(b);
            b.setAttribute("flex", "1");

            var position = this.tabs.length - 1;
            var uniqueId = "panel" + Date.now() + position;
            notificationbox.id = uniqueId;
            t.linkedPanel = uniqueId;
            t.linkedBrowser = b;
            t._tPos = position;
            if (t.previousSibling.selected)
              t.setAttribute("afterselected", true);

            // NB: this appendChild call causes us to run constructors for the
            // browser element, which fires off a bunch of notifications. Some
            // of those notifications can cause code to run that inspects our
            // state, so it is important that the tab element is fully
            // initialized by this point.
            this.mPanelContainer.appendChild(notificationbox);

            this.tabContainer.updateVisibility();

            // wire up a progress listener for the new browser object.
            var tabListener = this.mTabProgressListener(t, b, blank);
            const filter = Components.classes["@mozilla.org/appshell/component/browser-status-filter;1"]
                                     .createInstance(Components.interfaces.nsIWebProgress);
            filter.addProgressListener(tabListener, Components.interfaces.nsIWebProgress.NOTIFY_ALL);
            b.webProgress.addProgressListener(filter, Components.interfaces.nsIWebProgress.NOTIFY_ALL);
            this.mTabListeners[position] = tabListener;
            this.mTabFilters[position] = filter;

            b._fastFind = this.fastFind;
            b.droppedLinkHandler = handleDroppedLink;

            // Dispatch a new tab notification.  We do this once we're
            // entirely done, so that things are in a consistent state
            // even if the event listener opens or closes tabs.
            var evt = document.createEvent("Events");
            evt.initEvent("TabOpen", true, false);
            t.dispatchEvent(evt);

            if (!blank) {
              // Stop the existing about:blank load.  Otherwise, if aURI
              // doesn't stop in-progress loads on its own, we'll get into
              // trouble with multiple parallel loads running at once.
              b.stop();

              // pretend the user typed this so it'll be available till
              // the document successfully loads
              b.userTypedValue = aURI;

              let flags = Ci.nsIWebNavigation.LOAD_FLAGS_NONE;
              if (aAllowThirdPartyFixup)
                flags |= Ci.nsIWebNavigation.LOAD_FLAGS_ALLOW_THIRD_PARTY_FIXUP;
              if (aFromExternal)
                flags |= Ci.nsIWebNavigation.LOAD_FLAGS_FROM_EXTERNAL;
              try {
                b.loadURIWithFlags(aURI, flags, aReferrerURI, aCharset, aPostData);

                // We start our browsers out as inactive, and then maintain
                // activeness in the tab switcher.
                b.docShell.isActive = false;
              }
              catch (ex) { }
            }

            // Check if we're opening a tab related to the current tab and
            // move it to after the current tab.
            // aReferrerURI is null or undefined if the tab is opened from
            // an external application or bookmark, i.e. somewhere other
            // than the current tab.
            if ((aRelatedToCurrent == null ? aReferrerURI : aRelatedToCurrent) &&
                Services.prefs.getBoolPref("browser.tabs.insertRelatedAfterCurrent")) {
              let newTabPos = (this._lastRelatedTab ||
                               this.selectedTab)._tPos + 1;
              this.moveTabTo(t, newTabPos);
              this._lastRelatedTab = t;
            }

            return t;
          ]]>
        </body>
      </method>

      <method name="warnAboutClosingTabs">
      <parameter name="aAll"/>
      <body>
        <![CDATA[
          var tabsToClose = (aAll ? this.tabs.length : this.visibleTabs.length - 1)
                            - gBrowser._numPinnedTabs;
          if (tabsToClose <= 1)
            return true;

          const pref = "browser.tabs.warnOnClose";
          var shouldPrompt = Services.prefs.getBoolPref(pref);

          if (!shouldPrompt)
            return true;

          var ps = Services.prompt;

          // default to true: if it were false, we wouldn't get this far
          var warnOnClose = { value: true };
          var bundle = this.mStringBundle;

          // focus the window before prompting.
          // this will raise any minimized window, which will
          // make it obvious which window the prompt is for and will
          // solve the problem of windows "obscuring" the prompt.
          // see bug #350299 for more details
          window.focus();
          var buttonPressed =
            ps.confirmEx(window,
                         bundle.getString("tabs.closeWarningTitle"),
                         bundle.getFormattedString("tabs.closeWarningMultipleTabs",
                                                   [tabsToClose]),
                         (ps.BUTTON_TITLE_IS_STRING * ps.BUTTON_POS_0)
                         + (ps.BUTTON_TITLE_CANCEL * ps.BUTTON_POS_1),
                         bundle.getString("tabs.closeButtonMultiple"),
                         null, null,
                         bundle.getString('tabs.closeWarningPromptMe'),
                         warnOnClose);
          var reallyClose = (buttonPressed == 0);
          // don't set the pref unless they press OK and it's false
          if (reallyClose && !warnOnClose.value)
            Services.prefs.setBoolPref(pref, false);

          return reallyClose;
        ]]>
      </body>
      </method>

      <method name="removeAllTabsBut">
        <parameter name="aTab"/>
        <body>
          <![CDATA[
            if (aTab.pinned)
              return;

            if (this.warnAboutClosingTabs(false)) {
              let tabs = this.visibleTabs;
              this.selectedTab = aTab;

              for (let i = tabs.length - 1; i >= 0; --i) {
                if (tabs[i] != aTab && !tabs[i].pinned)
                  this.removeTab(tabs[i]);
              }
            }
          ]]>
        </body>
      </method>

      <method name="removeCurrentTab">
        <parameter name="aParams"/>
        <body>
          <![CDATA[
            this.removeTab(this.mCurrentTab, aParams);
          ]]>
        </body>
      </method>

      <field name="_removingTabs">
        []
      </field>

      <method name="removeTab">
        <parameter name="aTab"/>
        <parameter name="aParams"/>
        <body>
          <![CDATA[
            if (aParams)
              var animate = aParams.animate;

            // Handle requests for synchronously removing an already
            // asynchronously closing tab.
            if (!animate &&
                this._removingTabs.indexOf(aTab) > -1) {
              this._endRemoveTab(aTab);
              return;
            }

            var isLastTab = (this.tabs.length - this._removingTabs.length == 1);

            if (!this._beginRemoveTab(aTab, false, null, true))
              return;

            /* Don't animate if:
                - the caller didn't opt in
                - this is the last tab in the window
                - this is a pinned tab
                - a bunch of other tabs are already closing (arbitrary threshold)
                - the fadein attribute hasn't been set yet
                - browser.tabs.animate is false   */

            if (!animate ||
                isLastTab ||
                aTab.pinned ||
                this._removingTabs.length > 3 ||
                aTab.getAttribute("fadein") != "true" ||
                !Services.prefs.getBoolPref("browser.tabs.animate")) {
              this._endRemoveTab(aTab);
              return;
            }

            this._blurTab(aTab);
            aTab.removeAttribute("fadein");
          ]]>
        </body>
      </method>

      <!-- Tab close requests are ignored if the window is closing anyway,
           e.g. when holding Ctrl+W. -->
      <field name="_windowIsClosing">
        false
      </field>

      <method name="_beginRemoveTab">
        <parameter name="aTab"/>
        <parameter name="aTabWillBeMoved"/>
        <parameter name="aCloseWindowWithLastTab"/>
        <parameter name="aCloseWindowFastpath"/>
        <body>
          <![CDATA[
            if (this._removingTabs.indexOf(aTab) > -1 || this._windowIsClosing)
              return false;

            var browser = this.getBrowserForTab(aTab);

            if (!aTabWillBeMoved) {
              let ds = browser.docShell;
              if (ds && ds.contentViewer && !ds.contentViewer.permitUnload())
                return false;
            }

            var closeWindow = false;
            var newTab = false;
            if (this.tabs.length - this._removingTabs.length == 1) {
              closeWindow = aCloseWindowWithLastTab != null ? aCloseWindowWithLastTab :
                            !window.toolbar.visible ||
                              this.tabContainer._closeWindowWithLastTab;

              // Closing the tab and replacing it with a blank one is notably slower
              // than closing the window right away. If the caller opts in, take
              // the fast path.
              if (closeWindow &&
                  aCloseWindowFastpath &&
                  this._removingTabs.length == 0 &&
                  (this._windowIsClosing = window.closeWindow(true)))
                return null;

              newTab = true;
            }

            this._removingTabs.push(aTab);

            this.tabContainer.updateVisibility();

            // We're committed to closing the tab now.
            // Dispatch a notification.
            // We dispatch it before any teardown so that event listeners can
            // inspect the tab that's about to close.
            var evt = document.createEvent("UIEvent");
            evt.initUIEvent("TabClose", true, false, window, aTabWillBeMoved ? 1 : 0);
            aTab.dispatchEvent(evt);

            // Remove the tab's filter and progress listener.
            const filter = this.mTabFilters[aTab._tPos];
            browser.webProgress.removeProgressListener(filter);
            filter.removeProgressListener(this.mTabListeners[aTab._tPos]);
            this.mTabListeners[aTab._tPos].destroy();

            if (browser.registeredOpenURI) {
              this.mBrowserHistory.unregisterOpenPage(browser.registeredOpenURI);
              delete browser.registeredOpenURI;
            }

            // We are no longer the primary content area.
            browser.setAttribute("type", "content-targetable");

            // Remove this tab as the owner of any other tabs, since it's going away.
            Array.forEach(this.tabs, function (tab) {
              if ("owner" in tab && tab.owner == aTab)
                // |tab| is a child of the tab we're removing, make it an orphan
                tab.owner = null;
            });

            aTab._endRemoveArgs = [closeWindow, newTab];
            return true;
          ]]>
        </body>
      </method>

      <method name="_endRemoveTab">
        <parameter name="aTab"/>
        <body>
          <![CDATA[
            if (!aTab || !aTab._endRemoveArgs)
              return;

            var [aCloseWindow, aNewTab] = aTab._endRemoveArgs;
            aTab._endRemoveArgs = null;

            if (this._windowIsClosing) {
              aCloseWindow = false;
              aNewTab = false;
            }

            this._lastRelatedTab = null;

            // update the UI early for responsiveness
            aTab.collapsed = true;
            if (aNewTab)
              this.addTab("about:blank", {skipAnimation: true});
            this.tabContainer._fillTrailingGap();
            this._blurTab(aTab);

            this._removingTabs.splice(this._removingTabs.indexOf(aTab), 1);

            if (aCloseWindow) {
              this._windowIsClosing = true;
              while (this._removingTabs.length)
                this._endRemoveTab(this._removingTabs[0]);
            } else if (!this._windowIsClosing) {
              if (aNewTab)
                focusAndSelectUrlBar();

              // workaround for bug 345399
              this.tabContainer.mTabstrip._updateScrollButtonsDisabledState();
            }

            // We're going to remove the tab and the browser now.
            // Clean up mTabFilters and mTabListeners now rather than in
            // _beginRemoveTab, so that their size is always in sync with the
            // number of tabs and browsers (the xbl destructor depends on this).
            this.mTabFilters.splice(aTab._tPos, 1);
            this.mTabListeners.splice(aTab._tPos, 1);

            var browser = this.getBrowserForTab(aTab);

            // Because of the way XBL works (fields just set JS
            // properties on the element) and the code we have in place
            // to preserve the JS objects for any elements that have
            // JS properties set on them, the browser element won't be
            // destroyed until the document goes away.  So we force a
            // cleanup ourselves.
            // This has to happen before we remove the child so that the
            // XBL implementation of nsIObserver still works.
            browser.destroy();

            if (browser == this.mCurrentBrowser)
              this.mCurrentBrowser = null;

            var wasPinned = aTab.pinned;

            // Invalidate browsers cache, as the tab is removed from the
            // tab container.
            this._browsers = null;

            // Remove the tab ...
            this.tabContainer.removeChild(aTab);

            // ... and fix up the _tPos properties immediately.
            for (let i = aTab._tPos; i < this.tabs.length; i++)
              this.tabs[i]._tPos = i;

            if (!this._windowIsClosing) {
              if (wasPinned)
                this.tabContainer._positionPinnedTabs();

              // update tab close buttons state
              this.tabContainer.adjustTabstrip();
            }

            // update first-tab/last-tab/beforeselected/afterselected attributes
            this.selectedTab._selected = true;

            // Removing the panel requires fixing up selectedPanel immediately
            // (see below), which would be hindered by the potentially expensive
            // browser removal. So we remove the browser and the panel in two
            // steps.
            var panel = browser.parentNode;

            // This will unload the document. An unload handler could remove
            // dependant tabs, so it's important that the tabbrowser is now in
            // a consistent state (tab removed, tab positions updated, etc.).
            panel.removeChild(browser);

            // As the browser is removed, the removal of a dependent document can
            // cause the whole window to close. So at this point, it's possible
            // that the binding is destructed.
            if (this.mTabBox) {
              let selectedPanel = this.mTabBox.selectedPanel;

              this.mPanelContainer.removeChild(panel);

              // Under the hood, a selectedIndex attribute controls which panel
              // is displayed. Removing a panel A which precedes the selected
              // panel B makes selectedIndex point to the panel next to B. We
              // need to explicitly preserve B as the selected panel.
              this.mTabBox.selectedPanel = selectedPanel;
            }

            if (aCloseWindow)
              this._windowIsClosing = closeWindow(true);
          ]]>
        </body>
      </method>

      <method name="_blurTab">
        <parameter name="aTab"/>
        <body>
          <![CDATA[
            if (this.mCurrentTab != aTab)
              return;

            if (aTab.owner &&
                this._removingTabs.indexOf(aTab.owner) == -1 &&
                Services.prefs.getBoolPref("browser.tabs.selectOwnerOnClose")) {
              this.selectedTab = aTab.owner;
              return;
            }

            // Switch to a visible tab unless there aren't any others remaining
            let remainingTabs = this.visibleTabs;
            let numTabs = remainingTabs.length;
            if (numTabs == 0 || numTabs == 1 && remainingTabs[0] == aTab) {
              remainingTabs = Array.filter(this.tabs, function(tab) {
                return this._removingTabs.indexOf(tab) == -1;
              }, this);
            }

            // Try to find a remaining tab that comes after the given tab
            var tab = aTab;
            do {
              tab = tab.nextSibling;
            } while (tab && remainingTabs.indexOf(tab) == -1);

            if (!tab) {
              tab = aTab;

              do {
                tab = tab.previousSibling;
              } while (tab && remainingTabs.indexOf(tab) == -1);
            }

            this.selectedTab = tab;
          ]]>
        </body>
      </method>

      <method name="swapBrowsersAndCloseOther">
        <parameter name="aOurTab"/>
        <parameter name="aOtherTab"/>
        <body>
          <![CDATA[
            // That's gBrowser for the other window, not the tab's browser!
            var remoteBrowser = aOtherTab.ownerDocument.defaultView.gBrowser;

            // First, start teardown of the other browser.  Make sure to not
            // fire the beforeunload event in the process.  Close the other
            // window if this was its last tab.
            if (!remoteBrowser._beginRemoveTab(aOtherTab, true, true))
              return;

            // Unhook our progress listener
            var ourIndex = aOurTab._tPos;
            const filter = this.mTabFilters[ourIndex];
            var tabListener = this.mTabListeners[ourIndex];
            var ourBrowser = this.getBrowserForTab(aOurTab);
            ourBrowser.webProgress.removeProgressListener(filter);
            filter.removeProgressListener(tabListener);
            var tabListenerBlank = tabListener.mBlank;

            // Workarounds for bug 458697
            // Icon might have been set on DOMLinkAdded, don't override that.
            if (!ourBrowser.mIconURL && aOtherTab.linkedBrowser.mIconURL)
              this.setIcon(aOurTab, aOtherTab.linkedBrowser.mIconURL);
            var isBusy = aOtherTab.hasAttribute("busy");
            if (isBusy) {
              aOurTab.setAttribute("busy", "true");
              this._tabAttrModified(aOurTab);
              if (aOurTab == this.selectedTab)
                this.mIsBusy = true;
            }

            // Swap the docshells
            ourBrowser.swapDocShells(aOtherTab.linkedBrowser);

            // Finish tearing down the tab that's going away.
            remoteBrowser._endRemoveTab(aOtherTab);

            // Restore the progress listener
            tabListener = this.mTabProgressListener(aOurTab, ourBrowser,
                                                    tabListenerBlank);
            this.mTabListeners[ourIndex] = tabListener;
            filter.addProgressListener(tabListener,
              Components.interfaces.nsIWebProgress.NOTIFY_ALL);

            ourBrowser.webProgress.addProgressListener(filter,
              Components.interfaces.nsIWebProgress.NOTIFY_ALL);

            if (isBusy)
              this.setTabTitleLoading(aOurTab);
            else
              this.setTabTitle(aOurTab);
            this.updateIcon(aOurTab);

            // If the tab was already selected (this happpens in the scenario
            // of replaceTabWithWindow), notify onLocationChange, etc.
            if (aOurTab == this.selectedTab)
              this.updateCurrentBrowser(true);
          ]]>
        </body>
      </method>

      <method name="reloadAllTabs">
        <body>
          <![CDATA[
            let tabs = this.visibleTabs;
            let l = tabs.length;
            for (var i = 0; i < l; i++) {
              try {
                this.getBrowserForTab(tabs[i]).reload();
              } catch (e) {
                // ignore failure to reload so others will be reloaded
              }
            }
          ]]>
        </body>
      </method>

      <method name="reloadTab">
        <parameter name="aTab"/>
        <body>
          <![CDATA[
            this.getBrowserForTab(aTab).reload();
          ]]>
        </body>
      </method>

      <method name="addProgressListener">
        <parameter name="aListener"/>
        <parameter name="aMask"/>
        <body>
          <![CDATA[
            if (!this.mAddProgressListenerWasCalled) {
              this.mAddProgressListenerWasCalled = true;
              this.tabContainer.updateVisibility();
            }

            if (this.mProgressListeners.length == 1) {
              // If we are adding a 2nd progress listener, we need to enter tabbed mode
              // because the browser status filter can only handle one progress listener.
              // In tabbed mode, mTabProgressListener is used which will iterate over all listeners.
              this.enterTabbedMode();
            }

            this.mProgressListeners.push(aListener);

            if (!this.mTabbedMode) {
              // If someone does this:
              // addProgressListener, removeProgressListener, addProgressListener
              // don't create a new filter; reuse the existing filter.
              if (this.mTabFilters.length == 0) {
                // hook a filter up to our first browser
                const filter = Components.classes["@mozilla.org/appshell/component/browser-status-filter;1"]
                                         .createInstance(Components.interfaces.nsIWebProgress);
                this.mTabFilters[0] = filter;
                this.mCurrentBrowser.webProgress.addProgressListener(filter, Components.interfaces.nsIWebProgress.NOTIFY_ALL);
              }

              // Directly hook the listener up to the filter for better performance
              this.mTabFilters[0].addProgressListener(aListener, aMask);
            }
          ]]>
        </body>
      </method>

      <method name="removeProgressListener">
        <parameter name="aListener"/>
        <body>
          <![CDATA[
            this.mProgressListeners =
              this.mProgressListeners.filter(function (l) l != aListener);

            if (!this.mTabbedMode)
              // Don't forget to remove it from the filter we hooked it up to
              this.mTabFilters[0].removeProgressListener(aListener);
         ]]>
        </body>
      </method>

      <method name="addTabsProgressListener">
        <parameter name="aListener"/>
        <body>
          this.enterTabbedMode();
          this.mTabsProgressListeners.push(aListener);
        </body>
      </method>

      <method name="removeTabsProgressListener">
        <parameter name="aListener"/>
        <body>
        <![CDATA[
          this.mTabsProgressListeners =
            this.mTabsProgressListeners.filter(function (l) l != aListener);
        ]]>
        </body>
      </method>

      <method name="getBrowserForTab">
        <parameter name="aTab"/>
        <body>
        <![CDATA[
          return aTab.linkedBrowser;
        ]]>
        </body>
      </method>

      <method name="showOnlyTheseTabs">
        <parameter name="aTabs"/>
        <body>
        <![CDATA[
          Array.forEach(this.tabs, function(tab) {
            if (aTabs.indexOf(tab) == -1)
              this.hideTab(tab);
            else
              this.showTab(tab);
          }, this);
        ]]>
        </body>
      </method>

      <method name="showTab">
        <parameter name="aTab"/>
        <body>
        <![CDATA[
          if (aTab.hidden) {
            aTab.hidden = false;
            let event = document.createEvent("Events");
            event.initEvent("TabShow", true, false);
            aTab.dispatchEvent(event);
          }
        ]]>
        </body>
      </method>

      <method name="hideTab">
        <parameter name="aTab"/>
        <body>
        <![CDATA[
          if (!aTab.hidden && !aTab.pinned && !aTab.selected &&
              this._removingTabs.indexOf(aTab) == -1) {
            aTab.hidden = true;
            let event = document.createEvent("Events");
            event.initEvent("TabHide", true, false);
            aTab.dispatchEvent(event);
          }
        ]]>
        </body>
      </method>

      <method name="selectTabAtIndex">
        <parameter name="aIndex"/>
        <parameter name="aEvent"/>
        <body>
        <![CDATA[
          let tabs = this.visibleTabs;

          // count backwards for aIndex < 0
          if (aIndex < 0)
            aIndex += tabs.length;

          if (aIndex >= 0 && aIndex < tabs.length)
            this.selectedTab = tabs[aIndex];

          if (aEvent) {
            aEvent.preventDefault();
            aEvent.stopPropagation();
          }
        ]]>
        </body>
      </method>

      <property name="selectedTab">
        <getter>
          return this.mTabBox.selectedTab;
        </getter>
        <setter>
          <![CDATA[
          // Update the tab
          this.mTabBox.selectedTab = val;
          return val;
          ]]>
        </setter>
      </property>

      <property name="selectedBrowser"
                onget="return this.mCurrentBrowser;"
                readonly="true"/>

      <property name="browsers" readonly="true">
       <getter>
          <![CDATA[
            return this._browsers ||
                   (this._browsers = Array.map(this.tabs, function (tab) tab.linkedBrowser));
          ]]>
        </getter>
      </property>

      <!-- Moves a tab to a new browser window, unless it's already the only tab
           in the current window, in which case this will do nothing. -->
      <method name="replaceTabWithWindow">
        <parameter name="aTab"/>
        <body>
          <![CDATA[
            if (this.visibleTabs.length == 1)
              return null;

            // tell a new window to take the "dropped" tab
            return Services.ww.openWindow(window,
                                          getBrowserURL(),
                                          null,
                                          "chrome,dialog=no,all",
                                          aTab);
          ]]>
        </body>
      </method>

      <method name="moveTabTo">
        <parameter name="aTab"/>
        <parameter name="aIndex"/>
        <body>
        <![CDATA[
          var oldPosition = aTab._tPos;
          if (oldPosition == aIndex)
            return;

          // Don't allow mixing pinned and unpinned tabs.
          if (aTab.pinned)
            aIndex = Math.min(aIndex, this._numPinnedTabs - 1);
          else
            aIndex = Math.max(aIndex, this._numPinnedTabs);
          if (oldPosition == aIndex)
            return;

          this._lastRelatedTab = null;

          this.mTabFilters.splice(aIndex, 0, this.mTabFilters.splice(aTab._tPos, 1)[0]);
          this.mTabListeners.splice(aIndex, 0, this.mTabListeners.splice(aTab._tPos, 1)[0]);

          aIndex = aIndex < aTab._tPos ? aIndex: aIndex+1;
          this.mCurrentTab._selected = false;
          // use .item() instead of [] because dragging to the end of the strip goes out of
          // bounds: .item() returns null (so it acts like appendChild), but [] throws
          this.tabContainer.insertBefore(aTab, this.tabs.item(aIndex));
          // invalidate cache, because tabContainer is about to change
          this._browsers = null;

          for (let i = 0; i < this.tabs.length; i++) {
            this.tabs[i]._tPos = i;
            this.tabs[i]._selected = false;
          }
          this.mCurrentTab._selected = true;
          this.tabContainer.mTabstrip.ensureElementIsVisible(this.mCurrentTab, false);

          if (aTab.pinned)
            this.tabContainer._positionPinnedTabs();

          var evt = document.createEvent("UIEvents");
          evt.initUIEvent("TabMove", true, false, window, oldPosition);
          aTab.dispatchEvent(evt);
        ]]>
        </body>
      </method>

      <method name="moveTabForward">
        <body>
          <![CDATA[
            var tabPos = this.mCurrentTab._tPos;
            if (tabPos < this.browsers.length - 1) {
              this.moveTabTo(this.mCurrentTab, tabPos + 1);
              this.mCurrentTab.focus();
            }
            else if (this.arrowKeysShouldWrap)
              this.moveTabToStart();
          ]]>
        </body>
      </method>

      <method name="moveTabBackward">
        <body>
          <![CDATA[
            var tabPos = this.mCurrentTab._tPos;
            if (tabPos > 0) {
              this.moveTabTo(this.mCurrentTab, tabPos - 1);
              this.mCurrentTab.focus();
            }
            else if (this.arrowKeysShouldWrap)
              this.moveTabToEnd();
          ]]>
        </body>
      </method>

      <method name="moveTabToStart">
        <body>
          <![CDATA[
            var tabPos = this.mCurrentTab._tPos;
            if (tabPos > 0) {
              this.moveTabTo(this.mCurrentTab, 0);
              this.mCurrentTab.focus();
            }
          ]]>
        </body>
      </method>

      <method name="moveTabToEnd">
        <body>
          <![CDATA[
            var tabPos = this.mCurrentTab._tPos;
            if (tabPos < this.browsers.length - 1) {
              this.moveTabTo(this.mCurrentTab,
                             this.browsers.length - 1);
              this.mCurrentTab.focus();
            }
          ]]>
        </body>
      </method>

      <method name="moveTabOver">
        <parameter name="aEvent"/>
        <body>
          <![CDATA[
            var direction = window.getComputedStyle(this.parentNode, null).direction;
            if ((direction == "ltr" && aEvent.keyCode == KeyEvent.DOM_VK_RIGHT) ||
                (direction == "rtl" && aEvent.keyCode == KeyEvent.DOM_VK_LEFT))
              this.moveTabForward();
            else
              this.moveTabBackward();
          ]]>
        </body>
      </method>

      <method name="duplicateTab">
        <parameter name="aTab"/><!-- can be from a different window as well -->
        <body>
          <![CDATA[
            // try to have SessionStore duplicate the given tab
            try {
              var ss = Components.classes["@mozilla.org/browser/sessionstore;1"]
                                 .getService(Components.interfaces.nsISessionStore);
              return ss.duplicateTab(window, aTab);
            } catch (ex) {
              // fall back to basic URL copying
              return this.loadOneTab(this.getBrowserForTab(aTab).currentURI.spec);
            }
          ]]>
        </body>
      </method>

      <!-- BEGIN FORWARDED BROWSER PROPERTIES.  IF YOU ADD A PROPERTY TO THE BROWSER ELEMENT
           MAKE SURE TO ADD IT HERE AS WELL. -->
      <property name="canGoBack"
                onget="return this.mCurrentBrowser.canGoBack;"
                readonly="true"/>

      <property name="canGoForward"
                onget="return this.mCurrentBrowser.canGoForward;"
                readonly="true"/>

      <method name="goBack">
        <body>
          <![CDATA[
            return this.mCurrentBrowser.goBack();
          ]]>
        </body>
      </method>

      <method name="goForward">
        <body>
          <![CDATA[
            return this.mCurrentBrowser.goForward();
          ]]>
        </body>
      </method>

      <method name="reload">
        <body>
          <![CDATA[
            return this.mCurrentBrowser.reload();
          ]]>
        </body>
      </method>

      <method name="reloadWithFlags">
        <parameter name="aFlags"/>
        <body>
          <![CDATA[
            return this.mCurrentBrowser.reloadWithFlags(aFlags);
          ]]>
        </body>
      </method>

      <method name="stop">
        <body>
          <![CDATA[
            return this.mCurrentBrowser.stop();
          ]]>
        </body>
      </method>

      <!-- throws exception for unknown schemes -->
      <method name="loadURI">
        <parameter name="aURI"/>
        <parameter name="aReferrerURI"/>
        <parameter name="aCharset"/>
        <body>
          <![CDATA[
            return this.mCurrentBrowser.loadURI(aURI, aReferrerURI, aCharset);
          ]]>
        </body>
      </method>

      <!-- throws exception for unknown schemes -->
      <method name="loadURIWithFlags">
        <parameter name="aURI"/>
        <parameter name="aFlags"/>
        <parameter name="aReferrerURI"/>
        <parameter name="aCharset"/>
        <parameter name="aPostData"/>
        <body>
          <![CDATA[
            return this.mCurrentBrowser.loadURIWithFlags(aURI, aFlags, aReferrerURI, aCharset, aPostData);
          ]]>
        </body>
      </method>

      <method name="goHome">
        <body>
          <![CDATA[
            return this.mCurrentBrowser.goHome();
          ]]>
        </body>
      </method>

      <property name="homePage">
        <getter>
          <![CDATA[
            return this.mCurrentBrowser.homePage;
          ]]>
        </getter>
        <setter>
          <![CDATA[
            this.mCurrentBrowser.homePage = val;
            return val;
          ]]>
        </setter>
      </property>

      <method name="gotoIndex">
        <parameter name="aIndex"/>
        <body>
          <![CDATA[
            return this.mCurrentBrowser.gotoIndex(aIndex);
          ]]>
        </body>
      </method>

      <method name="attachFormFill">
        <body><![CDATA[
          for (var i = 0; i < this.mPanelContainer.childNodes.length; ++i) {
            var cb = this.getBrowserAtIndex(i);
            cb.attachFormFill();
          }
        ]]></body>
      </method>

      <method name="detachFormFill">
        <body><![CDATA[
          for (var i = 0; i < this.mPanelContainer.childNodes.length; ++i) {
            var cb = this.getBrowserAtIndex(i);
            cb.detachFormFill();
          }
        ]]></body>
      </method>

      <property name="pageReport"
                onget="return this.mCurrentBrowser.pageReport;"
                readonly="true"/>

      <property name="currentURI"
                onget="return this.mCurrentBrowser.currentURI;"
                readonly="true"/>

      <field name="_fastFind">null</field>
      <property name="fastFind"
                readonly="true">
        <getter>
        <![CDATA[
          if (!this._fastFind) {
            this._fastFind = Components.classes["@mozilla.org/typeaheadfind;1"]
                                       .createInstance(Components.interfaces.nsITypeAheadFind);
            this._fastFind.init(this.docShell);
          }
          return this._fastFind;
        ]]>
        </getter>
      </property>

      <property name="docShell"
                onget="return this.mCurrentBrowser.docShell"
                readonly="true"/>

      <property name="webNavigation"
                onget="return this.mCurrentBrowser.webNavigation"
                readonly="true"/>

      <property name="webBrowserFind"
                readonly="true"
                onget="return this.mCurrentBrowser.webBrowserFind"/>

      <property name="webProgress"
                readonly="true"
                onget="return this.mCurrentBrowser.webProgress"/>

      <property name="contentWindow"
                readonly="true"
                onget="return this.mCurrentBrowser.contentWindow"/>

      <property name="sessionHistory"
                onget="return this.mCurrentBrowser.sessionHistory;"
                readonly="true"/>

      <property name="markupDocumentViewer"
                onget="return this.mCurrentBrowser.markupDocumentViewer;"
                readonly="true"/>

      <property name="contentViewerEdit"
                onget="return this.mCurrentBrowser.contentViewerEdit;"
                readonly="true"/>

      <property name="contentViewerFile"
                onget="return this.mCurrentBrowser.contentViewerFile;"
                readonly="true"/>

      <property name="documentCharsetInfo"
                onget="return this.mCurrentBrowser.documentCharsetInfo;"
                readonly="true"/>

      <property name="contentDocument"
                onget="return this.mCurrentBrowser.contentDocument;"
                readonly="true"/>

      <property name="contentTitle"
                onget="return this.mCurrentBrowser.contentTitle;"
                readonly="true"/>

      <property name="contentPrincipal"
                onget="return this.mCurrentBrowser.contentPrincipal;"
                readonly="true"/>

      <property name="securityUI"
                onget="return this.mCurrentBrowser.securityUI;"
                readonly="true"/>

      <method name="_handleKeyEvent">
        <parameter name="aEvent"/>
        <body><![CDATA[
          if (!aEvent.isTrusted) {
            // Don't let untrusted events mess with tabs.
            return;
          }

          if (aEvent.altKey)
            return;

          // We need to take care of FAYT-watching as long as the findbar
          // isn't initialized.  The checks on aEvent are copied from
          // _shouldFastFind (see findbar.xml).
          if (!gFindBarInitialized &&
              !(aEvent.ctrlKey || aEvent.metaKey) &&
              !aEvent.getPreventDefault()) {
            let charCode = aEvent.charCode;
            if (charCode) {
              let char = String.fromCharCode(charCode);
              if (char == "'" || char == "/" ||
                  Services.prefs.getBoolPref("accessibility.typeaheadfind")) {
                gFindBar._onBrowserKeypress(aEvent);
                return;
              }
            }
          }

#ifdef XP_MACOSX
          if (!aEvent.metaKey)
            return;

          var offset = 1;
          switch (aEvent.charCode) {
            case '}'.charCodeAt(0):
              offset = -1;
            case '{'.charCodeAt(0):
              if (window.getComputedStyle(this, null).direction == "ltr")
                offset *= -1;
              this.tabContainer.advanceSelectedTab(offset, true);
              aEvent.stopPropagation();
              aEvent.preventDefault();
          }
#else
          if (aEvent.ctrlKey && !aEvent.shiftKey && !aEvent.metaKey &&
              aEvent.keyCode == KeyEvent.DOM_VK_F4 &&
              this.mTabBox.handleCtrlPageUpDown) {
            this.removeCurrentTab({animate: true});
            aEvent.stopPropagation();
            aEvent.preventDefault();
          }
#endif
        ]]></body>
      </method>

      <property name="userTypedClear"
                onget="return this.mCurrentBrowser.userTypedClear;"
                onset="return this.mCurrentBrowser.userTypedClear = val;"/>

      <property name="userTypedValue"
                onget="return this.mCurrentBrowser.userTypedValue;"
                onset="return this.mCurrentBrowser.userTypedValue = val;"/>

      <method name="createTooltip">
        <parameter name="event"/>
        <body><![CDATA[
          event.stopPropagation();
          var tab = document.tooltipNode;
          if (tab.localName != "tab") {
            event.preventDefault();
            return;
          }
          event.target.setAttribute("label", tab.mOverCloseButton ?
                                             tab.getAttribute("closetabtext") :
                                             tab.getAttribute("label"));
        ]]></body>
      </method>

      <method name="handleEvent">
        <parameter name="aEvent"/>
        <body><![CDATA[
          switch (aEvent.type) {
            case "keypress":
              this._handleKeyEvent(aEvent);
              break;
          }
        ]]></body>
      </method>

      <constructor>
        <![CDATA[
          this.mCurrentBrowser = this.mPanelContainer.childNodes[0].firstChild;
          this.mCurrentTab = this.tabContainer.firstChild;
          document.addEventListener("keypress", this, false);

          var uniqueId = "panel" + Date.now();
          this.mPanelContainer.childNodes[0].id = uniqueId;
          this.mCurrentTab.linkedPanel = uniqueId;
          this.mCurrentTab._tPos = 0;
          this.mCurrentTab.linkedBrowser = this.mCurrentBrowser;

          // set up the shared autoscroll popup
          this._autoScrollPopup = this.mCurrentBrowser._createAutoScrollPopup();
          this._autoScrollPopup.id = "autoscroller";
          this.appendChild(this._autoScrollPopup);
          this.mCurrentBrowser.setAttribute("autoscrollpopup", this._autoScrollPopup.id);
          this.mCurrentBrowser.droppedLinkHandler = handleDroppedLink;
        ]]>
      </constructor>

      <destructor>
        <![CDATA[
          for (var i = 0; i < this.mTabListeners.length; ++i) {
            let browser = this.getBrowserAtIndex(i);
            if (browser.registeredOpenURI) {
              this.mBrowserHistory.unregisterOpenPage(browser.registeredOpenURI);
              delete browser.registeredOpenURI;
            }
            browser.webProgress.removeProgressListener(this.mTabFilters[i]);
            this.mTabFilters[i].removeProgressListener(this.mTabListeners[i]);
            this.mTabFilters[i] = null;
            this.mTabListeners[i].destroy();
            this.mTabListeners[i] = null;
          }
          document.removeEventListener("keypress", this, false);
        ]]>
      </destructor>

      <!-- Deprecated stuff, implemented for backwards compatibility. -->
      <method name="setStripVisibilityTo">
        <parameter name="aShow"/>
        <body>
          this.tabContainer.visible = aShow;
        </body>
      </method>
      <method name="getStripVisibility">
        <body>
          return this.tabContainer.visible;
        </body>
      </method>
      <property name="mContextTab" readonly="true"
                onget="return TabContextMenu.contextTab;"/>
      <property name="mPrefs" readonly="true"
                onget="return Services.prefs;"/>
      <property name="mTabContainer" readonly="true"
                onget="return this.tabContainer;"/>
      <property name="mTabs" readonly="true"
                onget="return this.tabs;"/>
      <!--
        - Compatibility hack: several extensions depend on this property to
        - access the tab context menu or tab container, so keep that working for
        - now. Ideally we can remove this once extensions are using
        - tabbrowser.tabContextMenu and tabbrowser.tabContainer directly.
        -->
      <property name="mStrip" readonly="true">
        <getter>
        <![CDATA[
          return ({
            self: this,
            childNodes: [null, this.tabContextMenu, this.tabContainer],
            firstChild: { nextSibling: this.tabContextMenu },
            getElementsByAttribute: function (attr, attrValue) {
              if (attr == "anonid" && attrValue == "tabContextMenu")
                return [this.self.tabContextMenu];
              return [];
            },
            // Also support adding event listeners (forward to the tab container)
            addEventListener: function (a,b,c) { this.self.tabContainer.addEventListener(a,b,c); },
            removeEventListener: function (a,b,c) { this.self.tabContainer.removeEventListener(a,b,c); }
          });
        ]]>
        </getter>
      </property>
    </implementation>

    <handlers>
      <handler event="DOMWindowClose" phase="capturing">
        <![CDATA[
          if (!event.isTrusted)
            return;

          if (this.tabs.length == 1)
            return;

          var tab = this._getTabForContentWindow(event.target);
          if (tab) {
            this.removeTab(tab);
            event.preventDefault();
          }
        ]]>
      </handler>
      <handler event="DOMWillOpenModalDialog" phase="capturing">
        <![CDATA[
          if (!event.isTrusted)
            return;

          // We're about to open a modal dialog, make sure the opening
          // tab is brought to the front.
          this.selectedTab = this._getTabForContentWindow(event.target.top);
        ]]>
      </handler>
      <handler event="DOMTitleChanged">
        <![CDATA[
          if (!event.isTrusted)
            return;

          var contentWin = event.target.defaultView;
          if (contentWin != contentWin.top)
            return;

          var tab = this._getTabForContentWindow(contentWin);
          this.setTabTitle(tab);
          if (tab == this.mCurrentTab)
            this.updateTitlebar();
        ]]>
      </handler>
    </handlers>
  </binding>

  <binding id="tabbrowser-tabbox"
           extends="chrome://global/content/bindings/tabbox.xml#tabbox">
    <implementation>
      <property name="tabs" readonly="true"
                onget="return document.getBindingParent(this).tabContainer;"/>
    </implementation>
  </binding>

  <binding id="tabbrowser-arrowscrollbox" extends="chrome://global/content/bindings/scrollbox.xml#arrowscrollbox-clicktoscroll">
    <implementation>
      <!-- Override scrollbox.xml method, since our scrollbox's children are
           inherited from the binding parent -->
      <method name="_getScrollableElements">
        <body><![CDATA[
          return Array.filter(document.getBindingParent(this).childNodes,
                              this._canScrollToElement, this);
        ]]></body>
      </method>
      <method name="_canScrollToElement">
        <parameter name="tab"/>
        <body><![CDATA[
          return !tab.pinned && !tab.hidden;
        ]]></body>
      </method>
    </implementation>

    <handlers>
      <handler event="underflow"><![CDATA[
         if (event.detail == 0)
           return; // Ignore vertical events

         var tabs = document.getBindingParent(this);
         tabs.removeAttribute("overflow");

         tabs.tabbrowser._removingTabs.forEach(tabs.tabbrowser.removeTab,
                                               tabs.tabbrowser);

         tabs._positionPinnedTabs();
      ]]></handler>
      <handler event="overflow"><![CDATA[
         if (event.detail == 0)
           return; // Ignore vertical events

         var tabs = document.getBindingParent(this);
         tabs.setAttribute("overflow", "true");
         tabs._positionPinnedTabs();
      ]]></handler>
    </handlers>
  </binding>

  <binding id="tabbrowser-tabs"
           extends="chrome://global/content/bindings/tabbox.xml#tabs">
    <resources>
      <stylesheet src="chrome://browser/content/tabbrowser.css"/>
    </resources>

    <content>
      <xul:hbox align="start">
        <xul:image class="tab-drop-indicator" anonid="tab-drop-indicator" collapsed="true"/>
      </xul:hbox>
      <xul:arrowscrollbox anonid="arrowscrollbox" orient="horizontal" flex="1"
                          style="min-width: 1px;"
#ifndef XP_MACOSX
                          clicktoscroll="true"
#endif
                          class="tabbrowser-arrowscrollbox">
# This is a hack to circumvent bug 472020, otherwise the tabs show up on the
# right of the newtab button.
        <children includes="tab"/>
# This is to ensure anything extensions put here will go before the newtab
# button, necessary due to the previous hack.
        <children/>
        <xul:toolbarbutton class="tabs-newtab-button"
                           command="cmd_newNavigatorTab"
                           onclick="checkForMiddleClick(this, event);"
                           tooltiptext="&newTabButton.tooltip;"/>
      </xul:arrowscrollbox>
    </content>

    <implementation implements="nsIDOMEventListener">
      <constructor>
        <![CDATA[
          this.mTabClipWidth = Services.prefs.getIntPref("browser.tabs.tabClipWidth");
          this.mCloseButtons = Services.prefs.getIntPref("browser.tabs.closeButtons");
          this._closeWindowWithLastTab = Services.prefs.getBoolPref("browser.tabs.closeWindowWithLastTab");

          var tab = this.firstChild;
          tab.setAttribute("label",
                           this.tabbrowser.mStringBundle.getString("tabs.emptyTabTitle"));
          tab.setAttribute("crop", "end");
          tab.setAttribute("validate", "never");
          tab.setAttribute("onerror", "this.removeAttribute('image');");
          this.adjustTabstrip();

          Services.prefs.addObserver("browser.tabs.", this._prefObserver, false);
          window.addEventListener("resize", this, false);
        ]]>
      </constructor>

      <destructor>
        <![CDATA[
          Services.prefs.removeObserver("browser.tabs.", this._prefObserver);
        ]]>
      </destructor>

      <field name="tabbrowser" readonly="true">
        document.getElementById(this.getAttribute("tabbrowser"));
      </field>

      <field name="tabbox" readonly="true">
        this.tabbrowser.mTabBox;
      </field>

      <field name="contextMenu" readonly="true">
        document.getElementById("tabContextMenu");
      </field>

      <field name="mTabstripWidth">0</field>

      <field name="mTabstrip">
        document.getAnonymousElementByAttribute(this, "anonid", "arrowscrollbox");
      </field>

      <field name="_prefObserver"><![CDATA[({
        tabContainer: this,

        observe: function (subject, topic, data) {
          switch (data) {
            case "browser.tabs.closeButtons":
              this.tabContainer.mCloseButtons = Services.prefs.getIntPref(data);
              this.tabContainer.adjustTabstrip();
              break;
            case "browser.tabs.autoHide":
              this.tabContainer.updateVisibility();
              break;
            case "browser.tabs.closeWindowWithLastTab":
              this.tabContainer._closeWindowWithLastTab = Services.prefs.getBoolPref(data);
              this.tabContainer.adjustTabstrip();
              break;
          }
        }
      });]]></field>
      <field name="_blockDblClick">false</field>

      <field name="_tabDropIndicator">
        document.getAnonymousElementByAttribute(this, "anonid", "tab-drop-indicator");
      </field>

      <field name="_dragOverDelay">350</field>
      <field name="_dragTime">0</field>

      <field name="_container" readonly="true"><![CDATA[
        this.parentNode && this.parentNode.localName == "toolbar" ? this.parentNode : this;
      ]]></field>

      <property name="visible"
                onget="return !this._container.collapsed;">
        <setter><![CDATA[
          this._container.collapsed = !val;

          if (val)
            this.tabbrowser.enterTabbedMode();

          document.getElementById("menu_closeWindow").hidden = !val;
          document.getElementById("menu_close").setAttribute("label",
            this.tabbrowser.mStringBundle.getString(val ? "tabs.closeTab" : "tabs.close"));

          return val;
        ]]></setter>
      </property>

      <method name="updateVisibility">
        <body><![CDATA[
          if (this.childNodes.length - this.tabbrowser._removingTabs.length == 1 &&
              window.toolbar.visible)
            this.visible = !Services.prefs.getBoolPref("browser.tabs.autoHide");
          else
            this.visible = true;
        ]]></body>
      </method>

      <method name="adjustTabstrip">
        <body><![CDATA[
          // modes for tabstrip
          // 0 - activetab  = close button on active tab only
          // 1 - alltabs    = close buttons on all tabs
          // 2 - noclose    = no close buttons at all
          // 3 - closeatend = close button at the end of the tabstrip
          switch (this.mCloseButtons) {
          case 0:
            if (this.childNodes.length == 1 && this._closeWindowWithLastTab)
              this.setAttribute("closebuttons", "noclose");
            else
              this.setAttribute("closebuttons", "activetab");
            break;
          case 1:
            if (this.childNodes.length == 1) {
              if (this._closeWindowWithLastTab)
                this.setAttribute("closebuttons", "noclose");
              else
                this.setAttribute("closebuttons", "alltabs");
            } else {
              let tab = this.tabbrowser.visibleTabs[this.tabbrowser._numPinnedTabs];
              if (tab && tab.getBoundingClientRect().width > this.mTabClipWidth)
                this.setAttribute("closebuttons", "alltabs");
              else
                this.setAttribute("closebuttons", "activetab");
            }
            break;
          case 2:
          case 3:
            this.setAttribute("closebuttons", "noclose");
            break;
          }
          var tabstripClosebutton = document.getElementById("tabs-closebutton");
          if (tabstripClosebutton && tabstripClosebutton.parentNode == this._container)
            tabstripClosebutton.collapsed = this.mCloseButtons != 3;
        ]]></body>
      </method>

      <method name="_handleTabSelect">
        <body><![CDATA[
          this.mTabstrip.ensureElementIsVisible(this.selectedItem);
        ]]></body>
      </method>

      <method name="_fillTrailingGap">
        <body><![CDATA[
          try {
            // if we're at the right side (and not the logical end,
            // which is why this works for both LTR and RTL)
            // of the tabstrip, we need to ensure that we stay
            // completely scrolled to the right side
            var tabStrip = this.mTabstrip;
            if (tabStrip.scrollPosition + tabStrip.scrollClientSize >
                tabStrip.scrollSize)
              tabStrip.scrollByPixels(-1);
          } catch (e) {}
        ]]></body>
      </method>

      <method name="_positionPinnedTabs">
        <body><![CDATA[
          var width = 0;
          var scrollButtonWidth = this.getAttribute("overflow") != "true" ? 0 :
                                  this.mTabstrip._scrollButtonDown.scrollWidth;
          for (var i = this.tabbrowser._numPinnedTabs - 1; i >= 0; i--) {
            let tab = this.childNodes[i];
            width += tab.scrollWidth;
            tab.style.MozMarginStart = - (width + scrollButtonWidth) + "px";
          }
          this.style.MozMarginStart = width + "px";
          this.mTabstrip.ensureElementIsVisible(this.selectedItem, false);
        ]]></body>
      </method>

      <method name="handleEvent">
        <parameter name="aEvent"/>
        <body><![CDATA[
          switch (aEvent.type) {
            case "resize":
              var width = this.mTabstrip.boxObject.width;
              if (width != this.mTabstripWidth) {
                this.adjustTabstrip();
                this._fillTrailingGap();
                this._handleTabSelect();
                this.mTabstripWidth = width;
              }
              break;
          }
        ]]></body>
      </method>

      <field name="_animateElement">
        this.mTabstrip._scrollButtonDown;
      </field>

      <method name="_notifyBackgroundTab">
        <parameter name="aTab"/>
        <body><![CDATA[
          if (aTab.pinned)
            return;

          var scrollRect = this.mTabstrip.scrollClientRect;
          var tab = aTab.getBoundingClientRect();

          // Is the new tab already completely visible?
          if (scrollRect.left <= tab.left && tab.right <= scrollRect.right)
            return;

          if (this.mTabstrip.smoothScroll) {
            let selected = !this.selectedItem.pinned &&
                           this.selectedItem.getBoundingClientRect();

            // Can we make both the new tab and the selected tab completely visible?
            if (!selected ||
                Math.max(tab.right - selected.left, selected.right - tab.left) <=
                  scrollRect.width) {
              this.mTabstrip.ensureElementIsVisible(aTab);
              return;
            }

            this.mTabstrip._smoothScrollByPixels(this.mTabstrip._isRTLScrollbox ?
                                                 selected.right - scrollRect.right :
                                                 selected.left - scrollRect.left);
          }

          if (!this._animateElement.hasAttribute("notifybgtab")) {
            this._animateElement.setAttribute("notifybgtab", "true");
            setTimeout(function (ele) {
              ele.removeAttribute("notifybgtab");
            }, 150, this._animateElement);
          }
        ]]></body>
      </method>

      <method name="_getDragTargetTab">
        <parameter name="event"/>
        <body><![CDATA[
          return event.target.localName == "tab" ? event.target : null;
        ]]></body>
      </method>

      <method name="_getDropIndex">
        <parameter name="event"/>
        <body><![CDATA[
          var tabs = this.childNodes;
          var tab = this._getDragTargetTab(event);
          if (window.getComputedStyle(this, null).direction == "ltr") {
            for (let i = tab ? tab._tPos : 0; i < tabs.length; i++)
              if (event.screenX < tabs[i].boxObject.screenX + tabs[i].boxObject.width / 2) 
                return i;
          } else {
            for (let i = tab ? tab._tPos : 0; i < tabs.length; i++)
              if (event.screenX > tabs[i].boxObject.screenX + tabs[i].boxObject.width / 2)
                return i;
          }
          return tabs.length;
        ]]></body>
      </method>

      <method name="_setEffectAllowedForDataTransfer">
        <parameter name="event"/>
        <body><![CDATA[
          var dt = event.dataTransfer;
          // Disallow dropping multiple items
          if (dt.mozItemCount > 1)
            return dt.effectAllowed = "none";

          var types = dt.mozTypesAt(0);
          var sourceNode = null;
          // tabs are always added as the first type
          if (types[0] == TAB_DROP_TYPE) {
            var sourceNode = dt.mozGetDataAt(TAB_DROP_TYPE, 0);
            if (sourceNode instanceof XULElement &&
                sourceNode.localName == "tab" &&
                (sourceNode.parentNode == this ||
                 (sourceNode.ownerDocument.defaultView instanceof ChromeWindow &&
                  sourceNode.ownerDocument.documentElement.getAttribute("windowtype") == "navigator:browser"))) {
              if (sourceNode.parentNode == this &&
                  (event.screenX >= sourceNode.boxObject.screenX &&
                    event.screenX <= (sourceNode.boxObject.screenX +
                                       sourceNode.boxObject.width))) {
                return dt.effectAllowed = "none";
              }

              return dt.effectAllowed = "copyMove";
            }
          }

          if (browserDragAndDrop.canDropLink(event)) {
            // Here we need to do this manually
            return dt.effectAllowed = dt.dropEffect = "link";
          }
          return dt.effectAllowed = "none";
        ]]></body>
      </method>

      <method name="_continueScroll">
        <parameter name="event"/>
        <body><![CDATA[
          // Workaround for bug 481904: Dragging a tab stops scrolling at
          // the tab's position when dragging to the first/last tab and back.
          var t = this.selectedItem;
          if (event.screenX >= t.boxObject.screenX &&
              event.screenX <= t.boxObject.screenX + t.boxObject.width &&
              event.screenY >= t.boxObject.screenY &&
              event.screenY <= t.boxObject.screenY + t.boxObject.height)
            this.mTabstrip.ensureElementIsVisible(t);
        ]]></body>
      </method>

      <method name="_handleNewTab">
        <parameter name="tab"/>
        <body><![CDATA[
          if (tab.parentNode != this)
            return;

          this.adjustTabstrip();

          if (tab.getAttribute("selected") == "true") {
            this._fillTrailingGap();
            this._handleTabSelect();
          } else {
            this._notifyBackgroundTab(tab);
          }

          // XXXmano: this is a temporary workaround for bug 345399
          // We need to manually update the scroll buttons disabled state
          // if a tab was inserted to the overflow area or removed from it
          // without any scrolling and when the tabbar has already
          // overflowed.
          this.mTabstrip._updateScrollButtonsDisabledState();
        ]]></body>
      </method>
      
      <method name="_canAdvanceToTab">
        <parameter name="aTab"/>
        <body>
        <![CDATA[
          return this.tabbrowser._removingTabs.indexOf(aTab) == -1;
        ]]>
        </body>
      </method>

      <!-- Deprecated stuff, implemented for backwards compatibility. -->
      <property name="mTabstripClosebutton" readonly="true"
                onget="return document.getElementById('tabs-closebutton');"/>
      <property name="mAllTabsPopup" readonly="true"
                onget="return document.getElementById('alltabs-popup');"/>
    </implementation>

    <handlers>
      <handler event="TabSelect" action="this._handleTabSelect();"/>

      <handler event="transitionend"><![CDATA[
        if (event.propertyName != "max-width")
          return;

        var tab = event.target;

        if (tab.getAttribute("fadein") == "true")
          this._handleNewTab(tab);
        else if (this.tabbrowser._removingTabs.indexOf(tab) > -1)
          this.tabbrowser._endRemoveTab(tab);
      ]]></handler>

      <handler event="dblclick"><![CDATA[
        // See hack note in the tabbrowser-close-button binding
        if (!this._blockDblClick && event.button == 0 &&
            event.originalTarget.localName == "box")
          BrowserOpenTab();
      ]]></handler>

      <handler event="click"><![CDATA[
        if (event.button != 1)
          return;

        if (event.target.localName == "tab") {
          if (this.childNodes.length > 1 || !this._closeWindowWithLastTab)
            this.tabbrowser.removeTab(event.target, {animate: true});
        } else if (event.originalTarget.localName == "box") {
          BrowserOpenTab();
        } else {
          return;
        }

        event.stopPropagation();
      ]]></handler>

      <handler event="keypress"><![CDATA[
        if (event.altKey || event.shiftKey ||
#ifdef XP_MACOSX
            !event.metaKey)
#else
            !event.ctrlKey || event.metaKey)
#endif
          return;

        switch (event.keyCode) {
          case KeyEvent.DOM_VK_UP:
            this.tabbrowser.moveTabBackward();
            break;
          case KeyEvent.DOM_VK_DOWN:
            this.tabbrowser.moveTabForward();
            break;
          case KeyEvent.DOM_VK_RIGHT:
          case KeyEvent.DOM_VK_LEFT:
            this.tabbrowser.moveTabOver(event);
            break;
          case KeyEvent.DOM_VK_HOME:
            this.tabbrowser.moveTabToStart();
            break;
          case KeyEvent.DOM_VK_END:
            this.tabbrowser.moveTabToEnd();
            break;
          default:
            // Stop the keypress event for the above keyboard
            // shortcuts only.
            return;
        }
        event.stopPropagation();
        event.preventDefault();
      ]]></handler>

      <handler event="dragstart"><![CDATA[
        var tab = this._getDragTargetTab(event);
        if (!tab)
          return;

        let dt = event.dataTransfer;
        dt.mozSetDataAt(TAB_DROP_TYPE, tab, 0);
        let uri = this.tabbrowser.getBrowserForTab(tab).currentURI;
        let spec = uri ? uri.spec : "about:blank";

        // We must not set text/x-moz-url or text/plain data here,
        // otherwise trying to deatch the tab by dropping it on the desktop
        // may result in an "internet shortcut"
        dt.mozSetDataAt("text/x-moz-text-internal", spec, 0);

        // Set the cursor to an arrow during tab drags.
        dt.mozCursor = "default";

        let canvas = tabPreviews.capture(tab, false);
        dt.setDragImage(canvas, 0, 0);
        event.stopPropagation();
      ]]></handler>

      <handler event="dragover"><![CDATA[
        var effects = this._setEffectAllowedForDataTransfer(event);

        var ind = this._tabDropIndicator;
        if (effects == "" || effects == "none") {
          ind.collapsed = true;
          this._continueScroll(event);
          return;
        }
        event.preventDefault();
        event.stopPropagation();

        var tabStrip = this.mTabstrip;
        var ltr = (window.getComputedStyle(this, null).direction == "ltr");

        // autoscroll the tab strip if we drag over the scroll
        // buttons, even if we aren't dragging a tab, but then
        // return to avoid drawing the drop indicator
        var pixelsToScroll = 0;
        if (this.getAttribute("overflow") == "true") {
          var targetAnonid = event.originalTarget.getAttribute("anonid");
          switch (targetAnonid) {
            case "scrollbutton-up":
              pixelsToScroll = tabStrip.scrollIncrement * -1;
              break;
            case "scrollbutton-down":
              pixelsToScroll = tabStrip.scrollIncrement;
              break;
          }
          if (pixelsToScroll)
            tabStrip.scrollByPixels((ltr ? 1 : -1) * pixelsToScroll);
        }

        if (effects == "link") {
          let tab = this._getDragTargetTab(event);
          if (tab) {
            if (!this._dragTime)
              this._dragTime = Date.now();
            if (Date.now() >= this._dragTime + this._dragOverDelay)
              this.selectedItem = tab;
            return;
          }
        }

        var newIndex = this._getDropIndex(event);
        var scrollRect = tabStrip.scrollClientRect;
        var rect = this.getBoundingClientRect();
        var minMargin = scrollRect.left - rect.left;
        var maxMargin = Math.min(minMargin + scrollRect.width, 
                                 scrollRect.right);
        if (!ltr)
          [minMargin, maxMargin] = [this.clientWidth - maxMargin,
                                    this.clientWidth - minMargin];
        var newMargin;
        if (pixelsToScroll) {
          // if we are scrolling, put the drop indicator at the edge
          // so that it doesn't jump while scrolling
          newMargin = (pixelsToScroll > 0) ? maxMargin : minMargin;
        }
        else {
          if (newIndex == this.childNodes.length) {
            let tabRect = this.childNodes[newIndex-1].getBoundingClientRect();
            if (ltr)
              newMargin = tabRect.right - rect.left;
            else
              newMargin = rect.right - tabRect.left;
          }
          else {
            let tabRect = this.childNodes[newIndex].getBoundingClientRect();
            if (ltr)
              newMargin = tabRect.left - rect.left;
            else
              newMargin = rect.right - tabRect.right;
          }
        }

        ind.collapsed = false;

        newMargin += ind.clientWidth / 2;
        if (!ltr)
          newMargin *= -1;

        ind.style.MozTransform = "translate(" + Math.round(newMargin) + "px)";
        ind.style.MozMarginStart = (-ind.clientWidth) + "px";
        ind.style.marginTop = (-ind.clientHeight) + "px";
      ]]></handler>

      <handler event="drop"><![CDATA[
        var dt = event.dataTransfer;
        var dropEffect = dt.dropEffect;
        var draggedTab;
        if (dropEffect != "link") { // copy or move
          draggedTab = dt.mozGetDataAt(TAB_DROP_TYPE, 0);
          // not our drop then
          if (!draggedTab)
            return;
        }

        this._tabDropIndicator.collapsed = true;
        event.stopPropagation();

        if (draggedTab && (dropEffect == "copy" ||
            draggedTab.parentNode == this)) {
          let newIndex = this._getDropIndex(event);
          if (dropEffect == "copy") {
            // copy the dropped tab (wherever it's from)
            let newTab = this.tabbrowser.duplicateTab(draggedTab);
            this.tabbrowser.moveTabTo(newTab, newIndex);
            if (draggedTab.parentNode != this || event.shiftKey)
              this.selectedItem = newTab;
          } else {
            // move the dropped tab
            if (newIndex > draggedTab._tPos)
              newIndex--;

            if (draggedTab.pinned) {
              if (newIndex >= this.tabbrowser._numPinnedTabs)
                this.tabbrowser.unpinTab(draggedTab);
            } else {
              if (newIndex <= this.tabbrowser._numPinnedTabs - 1)
                this.tabbrowser.pinTab(draggedTab);
            }

            this.tabbrowser.moveTabTo(draggedTab, newIndex);
          }
        } else if (draggedTab) {
          // swap the dropped tab with a new one we create and then close
          // it in the other window (making it seem to have moved between
          // windows)
          let newIndex = this._getDropIndex(event);
          let newTab = this.tabbrowser.addTab("about:blank");
          let newBrowser = this.tabbrowser.getBrowserForTab(newTab);
          // Stop the about:blank load
          newBrowser.stop();
          // make sure it has a docshell
          newBrowser.docShell;

          this.tabbrowser.moveTabTo(newTab, newIndex);

          this.tabbrowser.swapBrowsersAndCloseOther(newTab, draggedTab);

          // We need to select the tab after we've done
          // swapBrowsersAndCloseOther, so that the updateCurrentBrowser
          // it triggers will correctly update our URL bar.
          this.tabbrowser.selectedTab = newTab;
        } else {
          let url = browserDragAndDrop.drop(event, { });

          // valid urls don't contain spaces ' '; if we have a space it isn't a valid url.
          // Also disallow dropping javascript: or data: urls--bail out
          if (!url || !url.length || url.indexOf(" ", 0) != -1 ||
              /^\s*(javascript|data):/.test(url))
            return;

          let bgLoad = Services.prefs.getBoolPref("browser.tabs.loadInBackground");

          if (event.shiftKey)
            bgLoad = !bgLoad;

          let tab = this._getDragTargetTab(event);
          if (!tab || dropEffect == "copy") {
            // We're adding a new tab.
            let newIndex = this._getDropIndex(event);
            let newTab = this.tabbrowser.loadOneTab(getShortcutOrURI(url), {inBackground: bgLoad});
            this.tabbrowser.moveTabTo(newTab, newIndex);
          } else {
            // Load in an existing tab.
            try {
              this.tabbrowser.getBrowserForTab(tab).loadURI(getShortcutOrURI(url));
              if (!bgLoad)
                this.selectedItem = tab;
            } catch(ex) {
              // Just ignore invalid urls
            }
          }
        }
      ]]></handler>

      <handler event="dragend"><![CDATA[
        // Note: while this case is correctly handled here, this event
        // isn't dispatched when the tab is moved within the tabstrip,
        // see bug 460801.

        // * mozUserCancelled = the user pressed ESC to cancel the drag
        var dt = event.dataTransfer;
        if (dt.mozUserCancelled || dt.dropEffect != "none")
          return;

        // Disable detach within the browser toolbox
        var eX = event.screenX;
        var wX = window.screenX;
        // check if the drop point is horizontally within the window
        if (eX > wX && eX < (wX + window.outerWidth)) {
          let bo = this.mTabstrip.boxObject;
          // also avoid detaching if the the tab was dropped too close to
          // the tabbar (half a tab)
          let endScreenY = bo.screenY + 1.5 * bo.height;
          let eY = event.screenY;
          if (eY < endScreenY && eY > window.screenY)
            return;
        }

        var draggedTab = dt.mozGetDataAt(TAB_DROP_TYPE, 0);
        this.tabbrowser.replaceTabWithWindow(draggedTab);
        event.stopPropagation();
      ]]></handler>

      <handler event="dragleave"><![CDATA[
        this._dragTime = 0;

        // This does not work at all (see bug 458613)
        var target = event.relatedTarget;
        while (target && target != this)
          target = target.parentNode;
        if (target)
          return;

        this._tabDropIndicator.collapsed = true;
        this._continueScroll(event);
        event.stopPropagation();
      ]]></handler>
    </handlers>
  </binding>

  <!-- close-tab-button binding
       This binding relies on the structure of the tabbrowser binding.
       Therefore it should only be used as a child of the tab or the tabs
       element (in both cases, when they are anonymous nodes of <tabbrowser>).
  -->
  <binding id="tabbrowser-close-tab-button"
           extends="chrome://global/content/bindings/toolbarbutton.xml#toolbarbutton-image">
    <handlers>
      <handler event="click" button="0"><![CDATA[
        var bindingParent = document.getBindingParent(this);
        var tabContainer = bindingParent.parentNode;
        /* The only sequence in which a second click event (i.e. dblclik)
         * can be dispatched on an in-tab close button is when it is shown
         * after the first click (i.e. the first click event was dispatched
         * on the tab). This happens when we show the close button only on
         * the active tab. (bug 352021)
         * The only sequence in which a third click event can be dispatched
         * on an in-tab close button is when the tab was opened with a
         * double click on the tabbar. (bug 378344)
         * In both cases, it is most likely that the close button area has
         * been accidentally clicked, therefore we do not close the tab.
         *
         * We don't want to ignore processing of more than one click event,
         * though, since the user might actually be repeatedly clicking to
         * close many tabs at once.
         */
        if (event.detail > 1 && !this._ignoredClick) {
          this._ignoredClick = true;
          return;
        }

        // Reset the "ignored click" flag
        this._ignoredClick = false;

        tabContainer.tabbrowser.removeTab(bindingParent, {animate: true});
        tabContainer._blockDblClick = true;

        /* XXXmano hack (see bug 343628):
         * Since we're removing the event target, if the user
         * double-clicks this button, the dblclick event will be dispatched
         * with the tabbar as its event target (and explicit/originalTarget),
         * which treats that as a mouse gesture for opening a new tab.
         * In this context, we're manually blocking the dblclick event
         * (see dblclick handler).
         */
        var clickedOnce = false;
        function enableDblClick(event) {
          if (event.detail == 1 && !clickedOnce) {
            clickedOnce = true;
            return;
          }
          setTimeout(function() {
            tabContainer._blockDblClick = false;
          }, 0);
          tabContainer.removeEventListener("click", enableDblClick, false);
        }
        tabContainer.addEventListener("click", enableDblClick, false);
      ]]></handler>

      <handler event="dblclick" button="0" phase="capturing">
        // for the one-close-button case
        event.stopPropagation();
      </handler>

      <handler event="dragstart">
        event.stopPropagation();
      </handler>
    </handlers>
  </binding>

  <binding id="tabbrowser-tab" display="xul:hbox"
           extends="chrome://global/content/bindings/tabbox.xml#tab">
    <resources>
      <stylesheet src="chrome://browser/content/tabbrowser.css"/>
    </resources>

    <content context="tabContextMenu" closetabtext="&closeTab.label;">
      <xul:image xbl:inherits="validate,src=image"
                 class="tab-icon-image"
                 role="presentation"/>
      <xul:label flex="1"
                 xbl:inherits="value=label,crop,accesskey"
                 class="tab-text"
                 role="presentation"/>
      <xul:toolbarbutton anonid="close-button"
                         tabindex="-1"
                         clickthrough="never"
                         class="tab-close-button"/>
    </content>

    <implementation>
      <property name="pinned" readonly="true">
        <getter>
          return this.getAttribute("pinned") == "true";
        </getter>
      </property>

      <field name="mOverCloseButton">false</field>
      <field name="mCorrespondingMenuitem">null</field>
    </implementation>

    <handlers>
      <handler event="mouseover">
        var anonid = event.originalTarget.getAttribute("anonid");
        if (anonid == "close-button")
          this.mOverCloseButton = true;
      </handler>
      <handler event="mouseout">
        var anonid = event.originalTarget.getAttribute("anonid");
        if (anonid == "close-button")
          this.mOverCloseButton = false;
      </handler>
      <handler event="dragstart" phase="capturing">
        this.style.MozUserFocus = '';
      </handler>
      <handler event="mousedown" button="0" phase="capturing">
      <![CDATA[
        if (this.mOverCloseButton) {
          event.stopPropagation();
        }
        else {
          this.style.MozUserFocus = 'ignore';
          this.clientTop; // just using this to flush style updates
        }
      ]]>
      </handler>
      <handler event="mousedown" button="1">
        this.style.MozUserFocus = 'ignore';
        this.clientTop;
      </handler>
      <handler event="mousedown" button="2">
        this.style.MozUserFocus = 'ignore';
        this.clientTop;
      </handler>
      <handler event="mouseup">
        this.style.MozUserFocus = '';
      </handler>
    </handlers>
  </binding>

  <binding id="tabbrowser-alltabs-popup"
           extends="chrome://global/content/bindings/popup.xml#popup">
    <implementation implements="nsIDOMEventListener">
      <method name="_menuItemOnCommand">
        <parameter name="aEvent"/>
        <body><![CDATA[
          gBrowser.selectedTab = aEvent.target.tab;
        ]]></body>
      </method>

      <method name="_tabOnAttrModified">
        <parameter name="aEvent"/>
        <body><![CDATA[
          var tab = aEvent.target;
          this._setMenuitemAttributes(tab.mCorrespondingMenuitem, tab);
        ]]></body>
      </method>

      <method name="_tabOnTabClose">
        <parameter name="aEvent"/>
        <body><![CDATA[
          var menuItem = aEvent.target.mCorrespondingMenuitem;
          if (menuItem)
            this.removeChild(menuItem);
        ]]></body>
      </method>

      <method name="handleEvent">
        <parameter name="aEvent"/>
        <body><![CDATA[
          if (!aEvent.isTrusted)
            return;

          switch (aEvent.type) {
            case "command":
              this._menuItemOnCommand(aEvent);
              break;
            case "TabAttrModified":
              this._tabOnAttrModified(aEvent);
              break;
            case "TabClose":
              this._tabOnTabClose(aEvent);
              break;
            case "TabOpen":
              this._createTabMenuItem(aEvent.originalTarget);
              break;
            case "scroll":
              this._updateTabsVisibilityStatus();
              break;
          }
        ]]></body>
      </method>

      <method name="_updateTabsVisibilityStatus">
        <body><![CDATA[
          var tabContainer = gBrowser.tabContainer;
          // We don't want menu item decoration unless there is overflow.
          if (tabContainer.getAttribute("overflow") != "true")
            return;

          var tabstripBO = tabContainer.mTabstrip.scrollBoxObject;
          for (var i = 0; i < this.childNodes.length; i++) {
            var curTabBO = this.childNodes[i].tab.boxObject;
            if (curTabBO.screenX >= tabstripBO.screenX &&
                curTabBO.screenX + curTabBO.width <= tabstripBO.screenX + tabstripBO.width)
              this.childNodes[i].setAttribute("tabIsVisible", "true"); 
            else
              this.childNodes[i].removeAttribute("tabIsVisible");
          }
        ]]></body>
      </method>

      <method name="_createTabMenuItem">
        <parameter name="aTab"/>
        <body><![CDATA[
          var menuItem = document.createElementNS(
            "http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul", 
            "menuitem");

          menuItem.setAttribute("class", "menuitem-iconic alltabs-item menuitem-with-favicon");

          this._setMenuitemAttributes(menuItem, aTab);

          // Keep some attributes of the menuitem in sync with its
          // corresponding tab (e.g. the tab label)
          aTab.mCorrespondingMenuitem = menuItem;
          menuItem.tab = aTab;
          menuItem.addEventListener("command", this, false);

          this.appendChild(menuItem);
          return menuItem;
        ]]></body>
      </method>

      <method name="_setMenuitemAttributes">
        <parameter name="aMenuitem"/>
        <parameter name="aTab"/>
        <body><![CDATA[
          aMenuitem.setAttribute("label", aTab.label);
          aMenuitem.setAttribute("crop", aTab.getAttribute("crop"));
          aMenuitem.setAttribute("image", aTab.getAttribute("image"));

          if (aTab.hasAttribute("busy"))
            aMenuitem.setAttribute("busy", aTab.getAttribute("busy"));
          else
            aMenuitem.removeAttribute("busy");

          if (aTab.selected)
            aMenuitem.setAttribute("selected", "true");
          else
            aMenuitem.removeAttribute("selected");
        ]]></body>
      </method>
    </implementation>

    <handlers>
      <handler event="popupshowing">
      <![CDATA[
        // set up the menu popup
        var tabcontainer = gBrowser.tabContainer;
        let tabs = gBrowser.visibleTabs;

        // Listen for changes in the tab bar.
        tabcontainer.addEventListener("TabOpen", this, false);
        tabcontainer.addEventListener("TabAttrModified", this, false);
        tabcontainer.addEventListener("TabClose", this, false);
        tabcontainer.mTabstrip.addEventListener("scroll", this, false);

        for (var i = 0; i < tabs.length; i++) {
          this._createTabMenuItem(tabs[i]);
        }
        this._updateTabsVisibilityStatus();
      ]]></handler>

      <handler event="popuphidden">
      <![CDATA[
        // clear out the menu popup and remove the listeners
        while (this.hasChildNodes()) {
          var menuItem = this.lastChild;
          menuItem.removeEventListener("command", this, false);
          menuItem.tab.mCorrespondingMenuitem = null;
          this.removeChild(menuItem);
        }
        var tabcontainer = gBrowser.tabContainer;
        tabcontainer.mTabstrip.removeEventListener("scroll", this, false);
        tabcontainer.removeEventListener("TabOpen", this, false);
        tabcontainer.removeEventListener("TabAttrModified", this, false);
        tabcontainer.removeEventListener("TabClose", this, false);
      ]]></handler>

      <handler event="DOMMenuItemActive">
      <![CDATA[
        var tab = event.target.tab;
        if (tab) {
          var statusText = tab.linkedBrowser.currentURI.spec;
          if (statusText == "about:blank") {
            // XXXhack: Passing a space here (and not "")
            // to make sure the the browser implementation would
            // still consider it a hovered link.
            statusText = " ";
          }

          XULBrowserWindow.setOverLink(statusText, null);
        }
      ]]></handler>

      <handler event="DOMMenuItemInactive">
      <![CDATA[
        XULBrowserWindow.setOverLink("", null);
      ]]></handler>

    </handlers>
  </binding>

</bindings>