diff -r 000000000000 -r 6474c204b198 browser/components/customizableui/src/CustomizeMode.jsm
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/browser/components/customizableui/src/CustomizeMode.jsm	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,2004 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+"use strict";
+
+this.EXPORTED_SYMBOLS = ["CustomizeMode"];
+
+const {classes: Cc, interfaces: Ci, utils: Cu, results: Cr} = Components;
+
+const kPrefCustomizationDebug = "browser.uiCustomization.debug";
+const kPrefCustomizationAnimation = "browser.uiCustomization.disableAnimation";
+const kPaletteId = "customization-palette";
+const kAboutURI = "about:customizing";
+const kDragDataTypePrefix = "text/toolbarwrapper-id/";
+const kPlaceholderClass = "panel-customization-placeholder";
+const kSkipSourceNodePref = "browser.uiCustomization.skipSourceNodeCheck";
+const kToolbarVisibilityBtn = "customization-toolbar-visibility-button";
+const kDrawInTitlebarPref = "browser.tabs.drawInTitlebar";
+const kMaxTransitionDurationMs = 2000;
+
+const kPanelItemContextMenu = "customizationPanelItemContextMenu";
+const kPaletteItemContextMenu = "customizationPaletteItemContextMenu";
+
+Cu.import("resource://gre/modules/Services.jsm");
+Cu.import("resource:///modules/CustomizableUI.jsm");
+Cu.import("resource://gre/modules/XPCOMUtils.jsm");
+Cu.import("resource://gre/modules/Task.jsm");
+Cu.import("resource://gre/modules/Promise.jsm");
+
+XPCOMUtils.defineLazyModuleGetter(this, "DragPositionManager",
+                                  "resource:///modules/DragPositionManager.jsm");
+XPCOMUtils.defineLazyModuleGetter(this, "BrowserUITelemetry",
+                                  "resource:///modules/BrowserUITelemetry.jsm");
+
+let gModuleName = "[CustomizeMode]";
+#include logging.js
+
+let gDisableAnimation = null;
+
+let gDraggingInToolbars;
+
+function CustomizeMode(aWindow) {
+  if (gDisableAnimation === null) {
+    gDisableAnimation = Services.prefs.getPrefType(kPrefCustomizationAnimation) == Ci.nsIPrefBranch.PREF_BOOL &&
+                        Services.prefs.getBoolPref(kPrefCustomizationAnimation);
+  }
+  this.window = aWindow;
+  this.document = aWindow.document;
+  this.browser = aWindow.gBrowser;
+
+  // There are two palettes - there's the palette that can be overlayed with
+  // toolbar items in browser.xul. This is invisible, and never seen by the
+  // user. Then there's the visible palette, which gets populated and displayed
+  // to the user when in customizing mode.
+  this.visiblePalette = this.document.getElementById(kPaletteId);
+  this.paletteEmptyNotice = this.document.getElementById("customization-empty");
+  this.paletteSpacer = this.document.getElementById("customization-spacer");
+  this.tipPanel = this.document.getElementById("customization-tipPanel");
+#ifdef CAN_DRAW_IN_TITLEBAR
+  this._updateTitlebarButton();
+  Services.prefs.addObserver(kDrawInTitlebarPref, this, false);
+  this.window.addEventListener("unload", this);
+#endif
+};
+
+CustomizeMode.prototype = {
+  _changed: false,
+  _transitioning: false,
+  window: null,
+  document: null,
+  // areas is used to cache the customizable areas when in customization mode.
+  areas: null,
+  // When in customizing mode, we swap out the reference to the invisible
+  // palette in gNavToolbox.palette for our visiblePalette. This way, for the
+  // customizing browser window, when widgets are removed from customizable
+  // areas and added to the palette, they're added to the visible palette.
+  // _stowedPalette is a reference to the old invisible palette so we can
+  // restore gNavToolbox.palette to its original state after exiting
+  // customization mode.
+  _stowedPalette: null,
+  _dragOverItem: null,
+  _customizing: false,
+  _skipSourceNodeCheck: null,
+  _mainViewContext: null,
+
+  get panelUIContents() {
+    return this.document.getElementById("PanelUI-contents");
+  },
+
+  get _handler() {
+    return this.window.CustomizationHandler;
+  },
+
+  uninit: function() {
+#ifdef CAN_DRAW_IN_TITLEBAR
+    Services.prefs.removeObserver(kDrawInTitlebarPref, this);
+#endif
+  },
+
+  toggle: function() {
+    if (this._handler.isEnteringCustomizeMode || this._handler.isExitingCustomizeMode) {
+      this._wantToBeInCustomizeMode = !this._wantToBeInCustomizeMode;
+      return;
+    }
+    if (this._customizing) {
+      this.exit();
+    } else {
+      this.enter();
+    }
+  },
+
+  enter: function() {
+    this._wantToBeInCustomizeMode = true;
+
+    if (this._customizing || this._handler.isEnteringCustomizeMode) {
+      return;
+    }
+
+    // Exiting; want to re-enter once we've done that.
+    if (this._handler.isExitingCustomizeMode) {
+      LOG("Attempted to enter while we're in the middle of exiting. " +
+          "We'll exit after we've entered");
+      return;
+    }
+
+
+    // We don't need to switch to kAboutURI, or open a new tab at
+    // kAboutURI if we're already on it.
+    if (this.browser.selectedBrowser.currentURI.spec != kAboutURI) {
+      this.window.switchToTabHavingURI(kAboutURI, true, {
+        skipTabAnimation: true,
+      });
+      return;
+    }
+
+    let window = this.window;
+    let document = this.document;
+
+    this._handler.isEnteringCustomizeMode = true;
+
+    // Always disable the reset button at the start of customize mode, it'll be re-enabled
+    // if necessary when we finish entering:
+    let resetButton = this.document.getElementById("customization-reset-button");
+    resetButton.setAttribute("disabled", "true");
+
+    Task.spawn(function() {
+      // We shouldn't start customize mode until after browser-delayed-startup has finished:
+      if (!this.window.gBrowserInit.delayedStartupFinished) {
+        let delayedStartupDeferred = Promise.defer();
+        let delayedStartupObserver = function(aSubject) {
+          if (aSubject == this.window) {
+            Services.obs.removeObserver(delayedStartupObserver, "browser-delayed-startup-finished");
+            delayedStartupDeferred.resolve();
+          }
+        }.bind(this);
+        Services.obs.addObserver(delayedStartupObserver, "browser-delayed-startup-finished", false);
+        yield delayedStartupDeferred.promise;
+      }
+
+      let toolbarVisibilityBtn = document.getElementById(kToolbarVisibilityBtn);
+      let togglableToolbars = window.getTogglableToolbars();
+      let bookmarksToolbar = document.getElementById("PersonalToolbar");
+      if (togglableToolbars.length == 0) {
+        toolbarVisibilityBtn.setAttribute("hidden", "true");
+      } else {
+        toolbarVisibilityBtn.removeAttribute("hidden");
+      }
+
+      // Disable lightweight themes while in customization mode since
+      // they don't have large enough images to pad the full browser window.
+      if (this.document.documentElement._lightweightTheme)
+        this.document.documentElement._lightweightTheme.disable();
+
+      CustomizableUI.dispatchToolboxEvent("beforecustomization", {}, window);
+      CustomizableUI.notifyStartCustomizing(this.window);
+
+      // Add a keypress listener to the document so that we can quickly exit
+      // customization mode when pressing ESC.
+      document.addEventListener("keypress", this);
+
+      // Same goes for the menu button - if we're customizing, a click on the
+      // menu button means a quick exit from customization mode.
+      window.PanelUI.hide();
+      window.PanelUI.menuButton.addEventListener("command", this);
+      window.PanelUI.menuButton.open = true;
+      window.PanelUI.beginBatchUpdate();
+
+      // The menu panel is lazy, and registers itself when the popup shows. We
+      // need to force the menu panel to register itself, or else customization
+      // is really not going to work. We pass "true" to ensureReady to
+      // indicate that we're handling calling startBatchUpdate and
+      // endBatchUpdate.
+      if (!window.PanelUI.isReady()) {
+        yield window.PanelUI.ensureReady(true);
+      }
+
+      // Hide the palette before starting the transition for increased perf.
+      this.visiblePalette.hidden = true;
+      this.visiblePalette.removeAttribute("showing");
+
+      // Disable the button-text fade-out mask
+      // during the transition for increased perf.
+      let panelContents = window.PanelUI.contents;
+      panelContents.setAttribute("customize-transitioning", "true");
+
+      // Move the mainView in the panel to the holder so that we can see it
+      // while customizing.
+      let mainView = window.PanelUI.mainView;
+      let panelHolder = document.getElementById("customization-panelHolder");
+      panelHolder.appendChild(mainView);
+
+      let customizeButton = document.getElementById("PanelUI-customize");
+      customizeButton.setAttribute("enterLabel", customizeButton.getAttribute("label"));
+      customizeButton.setAttribute("label", customizeButton.getAttribute("exitLabel"));
+      customizeButton.setAttribute("enterTooltiptext", customizeButton.getAttribute("tooltiptext"));
+      customizeButton.setAttribute("tooltiptext", customizeButton.getAttribute("exitTooltiptext"));
+
+      this._transitioning = true;
+
+      let customizer = document.getElementById("customization-container");
+      customizer.parentNode.selectedPanel = customizer;
+      customizer.hidden = false;
+
+      yield this._doTransition(true);
+
+      // Let everybody in this window know that we're about to customize.
+      CustomizableUI.dispatchToolboxEvent("customizationstarting", {}, window);
+
+      this._mainViewContext = mainView.getAttribute("context");
+      if (this._mainViewContext) {
+        mainView.removeAttribute("context");
+      }
+
+      this._showPanelCustomizationPlaceholders();
+
+      yield this._wrapToolbarItems();
+      this.populatePalette();
+
+      this._addDragHandlers(this.visiblePalette);
+
+      window.gNavToolbox.addEventListener("toolbarvisibilitychange", this);
+
+      document.getElementById("PanelUI-help").setAttribute("disabled", true);
+      document.getElementById("PanelUI-quit").setAttribute("disabled", true);
+
+      this._updateResetButton();
+      this._updateUndoResetButton();
+
+      this._skipSourceNodeCheck = Services.prefs.getPrefType(kSkipSourceNodePref) == Ci.nsIPrefBranch.PREF_BOOL &&
+                                  Services.prefs.getBoolPref(kSkipSourceNodePref);
+
+      let customizableToolbars = document.querySelectorAll("toolbar[customizable=true]:not([autohide=true]):not([collapsed=true])");
+      for (let toolbar of customizableToolbars)
+        toolbar.setAttribute("customizing", true);
+
+      CustomizableUI.addListener(this);
+      window.PanelUI.endBatchUpdate();
+      this._customizing = true;
+      this._transitioning = false;
+
+      // Show the palette now that the transition has finished.
+      this.visiblePalette.hidden = false;
+      window.setTimeout(() => {
+        // Force layout reflow to ensure the animation runs,
+        // and make it async so it doesn't affect the timing.
+        this.visiblePalette.clientTop;
+        this.visiblePalette.setAttribute("showing", "true");
+      }, 0);
+      this.paletteSpacer.hidden = true;
+      this._updateEmptyPaletteNotice();
+
+      this.maybeShowTip(panelHolder);
+
+      this._handler.isEnteringCustomizeMode = false;
+      panelContents.removeAttribute("customize-transitioning");
+
+      CustomizableUI.dispatchToolboxEvent("customizationready", {}, window);
+      this._enableOutlinesTimeout = window.setTimeout(() => {
+        this.document.getElementById("nav-bar").setAttribute("showoutline", "true");
+        this.panelUIContents.setAttribute("showoutline", "true");
+        delete this._enableOutlinesTimeout;
+      }, 0);
+
+      // It's possible that we didn't enter customize mode via the menu panel,
+      // meaning we didn't kick off about:customizing preloading. If that's
+      // the case, let's kick it off for the next time we load this mode.
+      window.gCustomizationTabPreloader.ensurePreloading();
+      if (!this._wantToBeInCustomizeMode) {
+        this.exit();
+      }
+    }.bind(this)).then(null, function(e) {
+      ERROR(e);
+      // We should ensure this has been called, and calling it again doesn't hurt:
+      window.PanelUI.endBatchUpdate();
+      this._handler.isEnteringCustomizeMode = false;
+    }.bind(this));
+  },
+
+  exit: function() {
+    this._wantToBeInCustomizeMode = false;
+
+    if (!this._customizing || this._handler.isExitingCustomizeMode) {
+      return;
+    }
+
+    // Entering; want to exit once we've done that.
+    if (this._handler.isEnteringCustomizeMode) {
+      LOG("Attempted to exit while we're in the middle of entering. " +
+          "We'll exit after we've entered");
+      return;
+    }
+
+    if (this.resetting) {
+      LOG("Attempted to exit while we're resetting. " +
+          "We'll exit after resetting has finished.");
+      return;
+    }
+
+    this.hideTip();
+
+    this._handler.isExitingCustomizeMode = true;
+
+    if (this._enableOutlinesTimeout) {
+      this.window.clearTimeout(this._enableOutlinesTimeout);
+    } else {
+      this.document.getElementById("nav-bar").removeAttribute("showoutline");
+      this.panelUIContents.removeAttribute("showoutline");
+    }
+
+    this._removeExtraToolbarsIfEmpty();
+
+    CustomizableUI.removeListener(this);
+
+    this.document.removeEventListener("keypress", this);
+    this.window.PanelUI.menuButton.removeEventListener("command", this);
+    this.window.PanelUI.menuButton.open = false;
+
+    this.window.PanelUI.beginBatchUpdate();
+
+    this._removePanelCustomizationPlaceholders();
+
+    let window = this.window;
+    let document = this.document;
+    let documentElement = document.documentElement;
+
+    // Hide the palette before starting the transition for increased perf.
+    this.paletteSpacer.hidden = false;
+    this.visiblePalette.hidden = true;
+    this.visiblePalette.removeAttribute("showing");
+    this.paletteEmptyNotice.hidden = true;
+
+    // Disable the button-text fade-out mask
+    // during the transition for increased perf.
+    let panelContents = window.PanelUI.contents;
+    panelContents.setAttribute("customize-transitioning", "true");
+
+    // Disable the reset and undo reset buttons while transitioning:
+    let resetButton = this.document.getElementById("customization-reset-button");
+    let undoResetButton = this.document.getElementById("customization-undo-reset-button");
+    undoResetButton.hidden = resetButton.disabled = true;
+
+    this._transitioning = true;
+
+    Task.spawn(function() {
+      yield this.depopulatePalette();
+
+      yield this._doTransition(false);
+
+      let browser = document.getElementById("browser");
+      if (this.browser.selectedBrowser.currentURI.spec == kAboutURI) {
+        let custBrowser = this.browser.selectedBrowser;
+        if (custBrowser.canGoBack) {
+          // If there's history to this tab, just go back.
+          // Note that this throws an exception if the previous document has a
+          // problematic URL (e.g. about:idontexist)
+          try {
+            custBrowser.goBack();
+          } catch (ex) {
+            ERROR(ex);
+          }
+        } else {
+          // If we can't go back, we're removing the about:customization tab.
+          // We only do this if we're the top window for this window (so not
+          // a dialog window, for example).
+          if (window.getTopWin(true) == window) {
+            let customizationTab = this.browser.selectedTab;
+            if (this.browser.browsers.length == 1) {
+              window.BrowserOpenTab();
+            }
+            this.browser.removeTab(customizationTab);
+          }
+        }
+      }
+      browser.parentNode.selectedPanel = browser;
+      let customizer = document.getElementById("customization-container");
+      customizer.hidden = true;
+
+      window.gNavToolbox.removeEventListener("toolbarvisibilitychange", this);
+
+      DragPositionManager.stop();
+      this._removeDragHandlers(this.visiblePalette);
+
+      yield this._unwrapToolbarItems();
+
+      if (this._changed) {
+        // XXXmconley: At first, it seems strange to also persist the old way with
+        //             currentset - but this might actually be useful for switching
+        //             to old builds. We might want to keep this around for a little
+        //             bit.
+        this.persistCurrentSets();
+      }
+
+      // And drop all area references.
+      this.areas = [];
+
+      // Let everybody in this window know that we're starting to
+      // exit customization mode.
+      CustomizableUI.dispatchToolboxEvent("customizationending", {}, window);
+
+      window.PanelUI.setMainView(window.PanelUI.mainView);
+      window.PanelUI.menuButton.disabled = false;
+
+      let customizeButton = document.getElementById("PanelUI-customize");
+      customizeButton.setAttribute("exitLabel", customizeButton.getAttribute("label"));
+      customizeButton.setAttribute("label", customizeButton.getAttribute("enterLabel"));
+      customizeButton.setAttribute("exitTooltiptext", customizeButton.getAttribute("tooltiptext"));
+      customizeButton.setAttribute("tooltiptext", customizeButton.getAttribute("enterTooltiptext"));
+
+      // We have to use setAttribute/removeAttribute here instead of the
+      // property because the XBL property will be set later, and right
+      // now we'd be setting an expando, which breaks the XBL property.
+      document.getElementById("PanelUI-help").removeAttribute("disabled");
+      document.getElementById("PanelUI-quit").removeAttribute("disabled");
+
+      panelContents.removeAttribute("customize-transitioning");
+
+      // We need to set this._customizing to false before removing the tab
+      // or the TabSelect event handler will think that we are exiting
+      // customization mode for a second time.
+      this._customizing = false;
+
+      let mainView = window.PanelUI.mainView;
+      if (this._mainViewContext) {
+        mainView.setAttribute("context", this._mainViewContext);
+      }
+
+      if (this.document.documentElement._lightweightTheme)
+        this.document.documentElement._lightweightTheme.enable();
+
+      let customizableToolbars = document.querySelectorAll("toolbar[customizable=true]:not([autohide=true])");
+      for (let toolbar of customizableToolbars)
+        toolbar.removeAttribute("customizing");
+
+      this.window.PanelUI.endBatchUpdate();
+      this._changed = false;
+      this._transitioning = false;
+      this._handler.isExitingCustomizeMode = false;
+      CustomizableUI.dispatchToolboxEvent("aftercustomization", {}, window);
+      CustomizableUI.notifyEndCustomizing(window);
+
+      if (this._wantToBeInCustomizeMode) {
+        this.enter();
+      }
+    }.bind(this)).then(null, function(e) {
+      ERROR(e);
+      // We should ensure this has been called, and calling it again doesn't hurt:
+      window.PanelUI.endBatchUpdate();
+      this._handler.isExitingCustomizeMode = false;
+    }.bind(this));
+  },
+
+  /**
+   * The customize mode transition has 3 phases when entering:
+   * 1) Pre-customization mode
+   *    This is the starting phase of the browser.
+   * 2) customize-entering
+   *    This phase is a transition, optimized for smoothness.
+   * 3) customize-entered
+   *    After the transition completes, this phase draws all of the
+   *    expensive detail that isn't necessary during the second phase.
+   *
+   * Exiting customization mode has a similar set of phases, but in reverse
+   * order - customize-entered, customize-exiting, pre-customization mode.
+   *
+   * When in the customize-entering, customize-entered, or customize-exiting
+   * phases, there is a "customizing" attribute set on the main-window to simplify
+   * excluding certain styles while in any phase of customize mode.
+   */
+  _doTransition: function(aEntering) {
+    let deferred = Promise.defer();
+    let deck = this.document.getElementById("content-deck");
+
+    let customizeTransitionEnd = function(aEvent) {
+      if (aEvent != "timedout" &&
+          (aEvent.originalTarget != deck || aEvent.propertyName != "margin-left")) {
+        return;
+      }
+      this.window.clearTimeout(catchAllTimeout);
+      // Bug 962677: We let the event loop breathe for before we do the final
+      // stage of the transition to improve perceived performance.
+      this.window.setTimeout(function () {
+        deck.removeEventListener("transitionend", customizeTransitionEnd);
+
+        if (!aEntering) {
+          this.document.documentElement.removeAttribute("customize-exiting");
+          this.document.documentElement.removeAttribute("customizing");
+        } else {
+          this.document.documentElement.setAttribute("customize-entered", true);
+          this.document.documentElement.removeAttribute("customize-entering");
+        }
+        CustomizableUI.dispatchToolboxEvent("customization-transitionend", aEntering, this.window);
+
+        deferred.resolve();
+      }.bind(this), 0);
+    }.bind(this);
+    deck.addEventListener("transitionend", customizeTransitionEnd);
+
+    if (gDisableAnimation) {
+      this.document.getElementById("tab-view-deck").setAttribute("fastcustomizeanimation", true);
+    }
+    if (aEntering) {
+      this.document.documentElement.setAttribute("customizing", true);
+      this.document.documentElement.setAttribute("customize-entering", true);
+    } else {
+      this.document.documentElement.setAttribute("customize-exiting", true);
+      this.document.documentElement.removeAttribute("customize-entered");
+    }
+
+    let catchAll = () => customizeTransitionEnd("timedout");
+    let catchAllTimeout = this.window.setTimeout(catchAll, kMaxTransitionDurationMs);
+    return deferred.promise;
+  },
+
+  maybeShowTip: function(aAnchor) {
+    let shown = false;
+    const kShownPref = "browser.customizemode.tip0.shown";
+    try {
+      shown = Services.prefs.getBoolPref(kShownPref);
+    } catch (ex) {}
+    if (shown)
+      return;
+
+    let anchorNode = aAnchor || this.document.getElementById("customization-panelHolder");
+    let messageNode = this.tipPanel.querySelector(".customization-tipPanel-contentMessage");
+    if (!messageNode.childElementCount) {
+      // Put the tip contents in the popup.
+      let bundle = this.document.getElementById("bundle_browser");
+      const kLabelClass = "customization-tipPanel-link";
+      messageNode.innerHTML = bundle.getFormattedString("customizeTips.tip0", [
+        "<label class=\"customization-tipPanel-em\" value=\"" +
+          bundle.getString("customizeTips.tip0.hint") + "\"/>",
+        this.document.getElementById("bundle_brand").getString("brandShortName"),
+        "<label class=\"" + kLabelClass + " text-link\" value=\"" +
+        bundle.getString("customizeTips.tip0.learnMore") + "\"/>"
+      ]);
+
+      messageNode.querySelector("." + kLabelClass).addEventListener("click", () => {
+        let url = Services.urlFormatter.formatURLPref("browser.customizemode.tip0.learnMoreUrl");
+        let browser = this.browser;
+        browser.selectedTab = browser.addTab(url);
+        this.hideTip();
+      });
+    }
+
+    this.tipPanel.hidden = false;
+    this.tipPanel.openPopup(anchorNode);
+    Services.prefs.setBoolPref(kShownPref, true);
+  },
+
+  hideTip: function() {
+    this.tipPanel.hidePopup();
+  },
+
+  _getCustomizableChildForNode: function(aNode) {
+    // NB: adjusted from _getCustomizableParent to keep that method fast
+    // (it's used during drags), and avoid multiple DOM loops
+    let areas = CustomizableUI.areas;
+    // Caching this length is important because otherwise we'll also iterate
+    // over items we add to the end from within the loop.
+    let numberOfAreas = areas.length;
+    for (let i = 0; i < numberOfAreas; i++) {
+      let area = areas[i];
+      let areaNode = aNode.ownerDocument.getElementById(area);
+      let customizationTarget = areaNode && areaNode.customizationTarget;
+      if (customizationTarget && customizationTarget != areaNode) {
+        areas.push(customizationTarget.id);
+      }
+      let overflowTarget = areaNode.getAttribute("overflowtarget");
+      if (overflowTarget) {
+        areas.push(overflowTarget);
+      }
+    }
+    areas.push(kPaletteId);
+
+    while (aNode && aNode.parentNode) {
+      let parent = aNode.parentNode;
+      if (areas.indexOf(parent.id) != -1) {
+        return aNode;
+      }
+      aNode = parent;
+    }
+    return null;
+  },
+
+  addToToolbar: function(aNode) {
+    aNode = this._getCustomizableChildForNode(aNode);
+    if (aNode.localName == "toolbarpaletteitem" && aNode.firstChild) {
+      aNode = aNode.firstChild;
+    }
+    CustomizableUI.addWidgetToArea(aNode.id, CustomizableUI.AREA_NAVBAR);
+    if (!this._customizing) {
+      CustomizableUI.dispatchToolboxEvent("customizationchange");
+    }
+  },
+
+  addToPanel: function(aNode) {
+    aNode = this._getCustomizableChildForNode(aNode);
+    if (aNode.localName == "toolbarpaletteitem" && aNode.firstChild) {
+      aNode = aNode.firstChild;
+    }
+    CustomizableUI.addWidgetToArea(aNode.id, CustomizableUI.AREA_PANEL);
+    if (!this._customizing) {
+      CustomizableUI.dispatchToolboxEvent("customizationchange");
+    }
+  },
+
+  removeFromArea: function(aNode) {
+    aNode = this._getCustomizableChildForNode(aNode);
+    if (aNode.localName == "toolbarpaletteitem" && aNode.firstChild) {
+      aNode = aNode.firstChild;
+    }
+    CustomizableUI.removeWidgetFromArea(aNode.id);
+    if (!this._customizing) {
+      CustomizableUI.dispatchToolboxEvent("customizationchange");
+    }
+  },
+
+  populatePalette: function() {
+    let fragment = this.document.createDocumentFragment();
+    let toolboxPalette = this.window.gNavToolbox.palette;
+
+    try {
+      let unusedWidgets = CustomizableUI.getUnusedWidgets(toolboxPalette);
+      for (let widget of unusedWidgets) {
+        let paletteItem = this.makePaletteItem(widget, "palette");
+        fragment.appendChild(paletteItem);
+      }
+
+      this.visiblePalette.appendChild(fragment);
+      this._stowedPalette = this.window.gNavToolbox.palette;
+      this.window.gNavToolbox.palette = this.visiblePalette;
+    } catch (ex) {
+      ERROR(ex);
+    }
+  },
+
+  //XXXunf Maybe this should use -moz-element instead of wrapping the node?
+  //       Would ensure no weird interactions/event handling from original node,
+  //       and makes it possible to put this in a lazy-loaded iframe/real tab
+  //       while still getting rid of the need for overlays.
+  makePaletteItem: function(aWidget, aPlace) {
+    let widgetNode = aWidget.forWindow(this.window).node;
+    let wrapper = this.createOrUpdateWrapper(widgetNode, aPlace);
+    wrapper.appendChild(widgetNode);
+    return wrapper;
+  },
+
+  depopulatePalette: function() {
+    return Task.spawn(function() {
+      this.visiblePalette.hidden = true;
+      let paletteChild = this.visiblePalette.firstChild;
+      let nextChild;
+      while (paletteChild) {
+        nextChild = paletteChild.nextElementSibling;
+        let provider = CustomizableUI.getWidget(paletteChild.id).provider;
+        if (provider == CustomizableUI.PROVIDER_XUL) {
+          let unwrappedPaletteItem =
+            yield this.deferredUnwrapToolbarItem(paletteChild);
+          this._stowedPalette.appendChild(unwrappedPaletteItem);
+        } else if (provider == CustomizableUI.PROVIDER_API) {
+          //XXXunf Currently this doesn't destroy the (now unused) node. It would
+          //       be good to do so, but we need to keep strong refs to it in
+          //       CustomizableUI (can't iterate of WeakMaps), and there's the
+          //       question of what behavior wrappers should have if consumers
+          //       keep hold of them.
+          //widget.destroyInstance(widgetNode);
+        } else if (provider == CustomizableUI.PROVIDER_SPECIAL) {
+          this.visiblePalette.removeChild(paletteChild);
+        }
+
+        paletteChild = nextChild;
+      }
+      this.visiblePalette.hidden = false;
+      this.window.gNavToolbox.palette = this._stowedPalette;
+    }.bind(this)).then(null, ERROR);
+  },
+
+  isCustomizableItem: function(aNode) {
+    return aNode.localName == "toolbarbutton" ||
+           aNode.localName == "toolbaritem" ||
+           aNode.localName == "toolbarseparator" ||
+           aNode.localName == "toolbarspring" ||
+           aNode.localName == "toolbarspacer";
+  },
+
+  isWrappedToolbarItem: function(aNode) {
+    return aNode.localName == "toolbarpaletteitem";
+  },
+
+  deferredWrapToolbarItem: function(aNode, aPlace) {
+    let deferred = Promise.defer();
+
+    dispatchFunction(function() {
+      let wrapper = this.wrapToolbarItem(aNode, aPlace);
+      deferred.resolve(wrapper);
+    }.bind(this))
+
+    return deferred.promise;
+  },
+
+  wrapToolbarItem: function(aNode, aPlace) {
+    if (!this.isCustomizableItem(aNode)) {
+      return aNode;
+    }
+    let wrapper = this.createOrUpdateWrapper(aNode, aPlace);
+
+    // It's possible that this toolbar node is "mid-flight" and doesn't have
+    // a parent, in which case we skip replacing it. This can happen if a
+    // toolbar item has been dragged into the palette. In that case, we tell
+    // CustomizableUI to remove the widget from its area before putting the
+    // widget in the palette - so the node will have no parent.
+    if (aNode.parentNode) {
+      aNode = aNode.parentNode.replaceChild(wrapper, aNode);
+    }
+    wrapper.appendChild(aNode);
+    return wrapper;
+  },
+
+  createOrUpdateWrapper: function(aNode, aPlace, aIsUpdate) {
+    let wrapper;
+    if (aIsUpdate && aNode.parentNode && aNode.parentNode.localName == "toolbarpaletteitem") {
+      wrapper = aNode.parentNode;
+      aPlace = wrapper.getAttribute("place");
+    } else {
+      wrapper = this.document.createElement("toolbarpaletteitem");
+      // "place" is used by toolkit to add the toolbarpaletteitem-palette
+      // binding to a toolbarpaletteitem, which gives it a label node for when
+      // it's sitting in the palette.
+      wrapper.setAttribute("place", aPlace);
+    }
+
+
+    // Ensure the wrapped item doesn't look like it's in any special state, and
+    // can't be interactved with when in the customization palette.
+    if (aNode.hasAttribute("command")) {
+      wrapper.setAttribute("itemcommand", aNode.getAttribute("command"));
+      aNode.removeAttribute("command");
+    }
+
+    if (aNode.hasAttribute("observes")) {
+      wrapper.setAttribute("itemobserves", aNode.getAttribute("observes"));
+      aNode.removeAttribute("observes");
+    }
+
+    if (aNode.getAttribute("checked") == "true") {
+      wrapper.setAttribute("itemchecked", "true");
+      aNode.removeAttribute("checked");
+    }
+
+    if (aNode.hasAttribute("id")) {
+      wrapper.setAttribute("id", "wrapper-" + aNode.getAttribute("id"));
+    }
+
+    if (aNode.hasAttribute("label")) {
+      wrapper.setAttribute("title", aNode.getAttribute("label"));
+    } else if (aNode.hasAttribute("title")) {
+      wrapper.setAttribute("title", aNode.getAttribute("title"));
+    }
+
+    if (aNode.hasAttribute("flex")) {
+      wrapper.setAttribute("flex", aNode.getAttribute("flex"));
+    }
+
+    if (aPlace == "panel") {
+      if (aNode.classList.contains(CustomizableUI.WIDE_PANEL_CLASS)) {
+        wrapper.setAttribute("haswideitem", "true");
+      } else if (wrapper.hasAttribute("haswideitem")) {
+        wrapper.removeAttribute("haswideitem");
+      }
+    }
+
+    let removable = aPlace == "palette" || CustomizableUI.isWidgetRemovable(aNode);
+    wrapper.setAttribute("removable", removable);
+
+    let contextMenuAttrName = aNode.getAttribute("context") ? "context" :
+                                aNode.getAttribute("contextmenu") ? "contextmenu" : "";
+    let currentContextMenu = aNode.getAttribute(contextMenuAttrName);
+    let contextMenuForPlace = aPlace == "panel" ?
+                                kPanelItemContextMenu :
+                                kPaletteItemContextMenu;
+    if (aPlace != "toolbar") {
+      wrapper.setAttribute("context", contextMenuForPlace);
+    }
+    // Only keep track of the menu if it is non-default.
+    if (currentContextMenu &&
+        currentContextMenu != contextMenuForPlace) {
+      aNode.setAttribute("wrapped-context", currentContextMenu);
+      aNode.setAttribute("wrapped-contextAttrName", contextMenuAttrName)
+      aNode.removeAttribute(contextMenuAttrName);
+    } else if (currentContextMenu == contextMenuForPlace) {
+      aNode.removeAttribute(contextMenuAttrName);
+    }
+
+    // Only add listeners for newly created wrappers:
+    if (!aIsUpdate) {
+      wrapper.addEventListener("mousedown", this);
+      wrapper.addEventListener("mouseup", this);
+    }
+
+    return wrapper;
+  },
+
+  deferredUnwrapToolbarItem: function(aWrapper) {
+    let deferred = Promise.defer();
+    dispatchFunction(function() {
+      let item = null;
+      try {
+        item = this.unwrapToolbarItem(aWrapper);
+      } catch (ex) {
+        Cu.reportError(ex);
+      }
+      deferred.resolve(item);
+    }.bind(this));
+    return deferred.promise;
+  },
+
+  unwrapToolbarItem: function(aWrapper) {
+    if (aWrapper.nodeName != "toolbarpaletteitem") {
+      return aWrapper;
+    }
+    aWrapper.removeEventListener("mousedown", this);
+    aWrapper.removeEventListener("mouseup", this);
+
+    let place = aWrapper.getAttribute("place");
+
+    let toolbarItem = aWrapper.firstChild;
+    if (!toolbarItem) {
+      ERROR("no toolbarItem child for " + aWrapper.tagName + "#" + aWrapper.id);
+      aWrapper.remove();
+      return null;
+    }
+
+    if (aWrapper.hasAttribute("itemobserves")) {
+      toolbarItem.setAttribute("observes", aWrapper.getAttribute("itemobserves"));
+    }
+
+    if (aWrapper.hasAttribute("itemchecked")) {
+      toolbarItem.checked = true;
+    }
+
+    if (aWrapper.hasAttribute("itemcommand")) {
+      let commandID = aWrapper.getAttribute("itemcommand");
+      toolbarItem.setAttribute("command", commandID);
+
+      //XXX Bug 309953 - toolbarbuttons aren't in sync with their commands after customizing
+      let command = this.document.getElementById(commandID);
+      if (command && command.hasAttribute("disabled")) {
+        toolbarItem.setAttribute("disabled", command.getAttribute("disabled"));
+      }
+    }
+
+    let wrappedContext = toolbarItem.getAttribute("wrapped-context");
+    if (wrappedContext) {
+      let contextAttrName = toolbarItem.getAttribute("wrapped-contextAttrName");
+      toolbarItem.setAttribute(contextAttrName, wrappedContext);
+      toolbarItem.removeAttribute("wrapped-contextAttrName");
+      toolbarItem.removeAttribute("wrapped-context");
+    } else if (place == "panel") {
+      toolbarItem.setAttribute("context", kPanelItemContextMenu);
+    }
+
+    if (aWrapper.parentNode) {
+      aWrapper.parentNode.replaceChild(toolbarItem, aWrapper);
+    }
+    return toolbarItem;
+  },
+
+  _wrapToolbarItems: function() {
+    let window = this.window;
+    // Add drag-and-drop event handlers to all of the customizable areas.
+    return Task.spawn(function() {
+      this.areas = [];
+      for (let area of CustomizableUI.areas) {
+        let target = CustomizableUI.getCustomizeTargetForArea(area, window);
+        this._addDragHandlers(target);
+        for (let child of target.children) {
+          if (this.isCustomizableItem(child)) {
+            yield this.deferredWrapToolbarItem(child, CustomizableUI.getPlaceForItem(child));
+          }
+        }
+        this.areas.push(target);
+      }
+    }.bind(this)).then(null, ERROR);
+  },
+
+  _addDragHandlers: function(aTarget) {
+    aTarget.addEventListener("dragstart", this, true);
+    aTarget.addEventListener("dragover", this, true);
+    aTarget.addEventListener("dragexit", this, true);
+    aTarget.addEventListener("drop", this, true);
+    aTarget.addEventListener("dragend", this, true);
+  },
+
+  _wrapItemsInArea: function(target) {
+    for (let child of target.children) {
+      if (this.isCustomizableItem(child)) {
+        this.wrapToolbarItem(child, CustomizableUI.getPlaceForItem(child));
+      }
+    }
+  },
+
+  _removeDragHandlers: function(aTarget) {
+    aTarget.removeEventListener("dragstart", this, true);
+    aTarget.removeEventListener("dragover", this, true);
+    aTarget.removeEventListener("dragexit", this, true);
+    aTarget.removeEventListener("drop", this, true);
+    aTarget.removeEventListener("dragend", this, true);
+  },
+
+  _unwrapItemsInArea: function(target) {
+    for (let toolbarItem of target.children) {
+      if (this.isWrappedToolbarItem(toolbarItem)) {
+        this.unwrapToolbarItem(toolbarItem);
+      }
+    }
+  },
+
+  _unwrapToolbarItems: function() {
+    return Task.spawn(function() {
+      for (let target of this.areas) {
+        for (let toolbarItem of target.children) {
+          if (this.isWrappedToolbarItem(toolbarItem)) {
+            yield this.deferredUnwrapToolbarItem(toolbarItem);
+          }
+        }
+        this._removeDragHandlers(target);
+      }
+    }.bind(this)).then(null, ERROR);
+  },
+
+  _removeExtraToolbarsIfEmpty: function() {
+    let toolbox = this.window.gNavToolbox;
+    for (let child of toolbox.children) {
+      if (child.hasAttribute("customindex")) {
+        let placements = CustomizableUI.getWidgetIdsInArea(child.id);
+        if (!placements.length) {
+          CustomizableUI.removeExtraToolbar(child.id);
+        }
+      }
+    }
+  },
+
+  persistCurrentSets: function(aSetBeforePersisting)  {
+    let document = this.document;
+    let toolbars = document.querySelectorAll("toolbar[customizable='true'][currentset]");
+    for (let toolbar of toolbars) {
+      if (aSetBeforePersisting) {
+        let set = toolbar.currentSet;
+        toolbar.setAttribute("currentset", set);
+      }
+      // Persist the currentset attribute directly on hardcoded toolbars.
+      document.persist(toolbar.id, "currentset");
+    }
+  },
+
+  reset: function() {
+    this.resetting = true;
+    // Disable the reset button temporarily while resetting:
+    let btn = this.document.getElementById("customization-reset-button");
+    BrowserUITelemetry.countCustomizationEvent("reset");
+    btn.disabled = true;
+    return Task.spawn(function() {
+      this._removePanelCustomizationPlaceholders();
+      yield this.depopulatePalette();
+      yield this._unwrapToolbarItems();
+
+      CustomizableUI.reset();
+
+      yield this._wrapToolbarItems();
+      this.populatePalette();
+
+      this.persistCurrentSets(true);
+
+      this._updateResetButton();
+      this._updateUndoResetButton();
+      this._updateEmptyPaletteNotice();
+      this._showPanelCustomizationPlaceholders();
+      this.resetting = false;
+      if (!this._wantToBeInCustomizeMode) {
+        this.exit();
+      }
+    }.bind(this)).then(null, ERROR);
+  },
+
+  undoReset: function() {
+    this.resetting = true;
+
+    return Task.spawn(function() {
+      this._removePanelCustomizationPlaceholders();
+      yield this.depopulatePalette();
+      yield this._unwrapToolbarItems();
+
+      CustomizableUI.undoReset();
+
+      yield this._wrapToolbarItems();
+      this.populatePalette();
+
+      this.persistCurrentSets(true);
+
+      this._updateResetButton();
+      this._updateUndoResetButton();
+      this._updateEmptyPaletteNotice();
+      this.resetting = false;
+    }.bind(this)).then(null, ERROR);
+  },
+
+  _onToolbarVisibilityChange: function(aEvent) {
+    let toolbar = aEvent.target;
+    if (aEvent.detail.visible && toolbar.getAttribute("customizable") == "true") {
+      toolbar.setAttribute("customizing", "true");
+    } else {
+      toolbar.removeAttribute("customizing");
+    }
+    this._onUIChange();
+  },
+
+  onWidgetMoved: function(aWidgetId, aArea, aOldPosition, aNewPosition) {
+    this._onUIChange();
+  },
+
+  onWidgetAdded: function(aWidgetId, aArea, aPosition) {
+    this._onUIChange();
+  },
+
+  onWidgetRemoved: function(aWidgetId, aArea) {
+    this._onUIChange();
+  },
+
+  onWidgetBeforeDOMChange: function(aNodeToChange, aSecondaryNode, aContainer) {
+    if (aContainer.ownerDocument.defaultView != this.window || this.resetting) {
+      return;
+    }
+    if (aContainer.id == CustomizableUI.AREA_PANEL) {
+      this._removePanelCustomizationPlaceholders();
+    }
+    // If we get called for widgets that aren't in the window yet, they might not have
+    // a parentNode at all.
+    if (aNodeToChange.parentNode) {
+      this.unwrapToolbarItem(aNodeToChange.parentNode);
+    }
+    if (aSecondaryNode) {
+      this.unwrapToolbarItem(aSecondaryNode.parentNode);
+    }
+  },
+
+  onWidgetAfterDOMChange: function(aNodeToChange, aSecondaryNode, aContainer) {
+    if (aContainer.ownerDocument.defaultView != this.window || this.resetting) {
+      return;
+    }
+    // If the node is still attached to the container, wrap it again:
+    if (aNodeToChange.parentNode) {
+      let place = CustomizableUI.getPlaceForItem(aNodeToChange);
+      this.wrapToolbarItem(aNodeToChange, place);
+      if (aSecondaryNode) {
+        this.wrapToolbarItem(aSecondaryNode, place);
+      }
+    } else {
+      // If not, it got removed.
+
+      // If an API-based widget is removed while customizing, append it to the palette.
+      // The _applyDrop code itself will take care of positioning it correctly, if
+      // applicable. We need the code to be here so removing widgets using CustomizableUI's
+      // API also does the right thing (and adds it to the palette)
+      let widgetId = aNodeToChange.id;
+      let widget = CustomizableUI.getWidget(widgetId);
+      if (widget.provider == CustomizableUI.PROVIDER_API) {
+        let paletteItem = this.makePaletteItem(widget, "palette");
+        this.visiblePalette.appendChild(paletteItem);
+      }
+    }
+    if (aContainer.id == CustomizableUI.AREA_PANEL) {
+      this._showPanelCustomizationPlaceholders();
+    }
+  },
+
+  onWidgetDestroyed: function(aWidgetId) {
+    let wrapper = this.document.getElementById("wrapper-" + aWidgetId);
+    if (wrapper) {
+      let wasInPanel = wrapper.parentNode == this.panelUIContents;
+      wrapper.remove();
+      if (wasInPanel) {
+        this._showPanelCustomizationPlaceholders();
+      }
+    }
+  },
+
+  onWidgetAfterCreation: function(aWidgetId, aArea) {
+    // If the node was added to an area, we would have gotten an onWidgetAdded notification,
+    // plus associated DOM change notifications, so only do stuff for the palette:
+    if (!aArea) {
+      let widgetNode = this.document.getElementById(aWidgetId);
+      if (widgetNode) {
+        this.wrapToolbarItem(widgetNode, "palette");
+      } else {
+        let widget = CustomizableUI.getWidget(aWidgetId);
+        this.visiblePalette.appendChild(this.makePaletteItem(widget, "palette"));
+      }
+    }
+  },
+
+  onAreaNodeRegistered: function(aArea, aContainer) {
+    if (aContainer.ownerDocument == this.document) {
+      this._wrapItemsInArea(aContainer);
+      this._addDragHandlers(aContainer);
+      DragPositionManager.add(this.window, aArea, aContainer);
+      this.areas.push(aContainer);
+    }
+  },
+
+  onAreaNodeUnregistered: function(aArea, aContainer, aReason) {
+    if (aContainer.ownerDocument == this.document && aReason == CustomizableUI.REASON_AREA_UNREGISTERED) {
+      this._unwrapItemsInArea(aContainer);
+      this._removeDragHandlers(aContainer);
+      DragPositionManager.remove(this.window, aArea, aContainer);
+      let index = this.areas.indexOf(aContainer);
+      this.areas.splice(index, 1);
+    }
+  },
+
+  _onUIChange: function() {
+    this._changed = true;
+    if (!this.resetting) {
+      this._updateResetButton();
+      this._updateUndoResetButton();
+      this._updateEmptyPaletteNotice();
+    }
+    CustomizableUI.dispatchToolboxEvent("customizationchange");
+  },
+
+  _updateEmptyPaletteNotice: function() {
+    let paletteItems = this.visiblePalette.getElementsByTagName("toolbarpaletteitem");
+    this.paletteEmptyNotice.hidden = !!paletteItems.length;
+  },
+
+  _updateResetButton: function() {
+    let btn = this.document.getElementById("customization-reset-button");
+    btn.disabled = CustomizableUI.inDefaultState;
+  },
+
+  _updateUndoResetButton: function() {
+    let undoResetButton =  this.document.getElementById("customization-undo-reset-button");
+    undoResetButton.hidden = !CustomizableUI.canUndoReset;
+  },
+
+  handleEvent: function(aEvent) {
+    switch(aEvent.type) {
+      case "toolbarvisibilitychange":
+        this._onToolbarVisibilityChange(aEvent);
+        break;
+      case "dragstart":
+        this._onDragStart(aEvent);
+        break;
+      case "dragover":
+        this._onDragOver(aEvent);
+        break;
+      case "drop":
+        this._onDragDrop(aEvent);
+        break;
+      case "dragexit":
+        this._onDragExit(aEvent);
+        break;
+      case "dragend":
+        this._onDragEnd(aEvent);
+        break;
+      case "command":
+        if (aEvent.originalTarget == this.window.PanelUI.menuButton) {
+          this.exit();
+          aEvent.preventDefault();
+        }
+        break;
+      case "mousedown":
+        this._onMouseDown(aEvent);
+        break;
+      case "mouseup":
+        this._onMouseUp(aEvent);
+        break;
+      case "keypress":
+        if (aEvent.keyCode == aEvent.DOM_VK_ESCAPE) {
+          this.exit();
+        }
+        break;
+#ifdef CAN_DRAW_IN_TITLEBAR
+      case "unload":
+        this.uninit();
+        break;
+#endif
+    }
+  },
+
+#ifdef CAN_DRAW_IN_TITLEBAR
+  observe: function(aSubject, aTopic, aData) {
+    switch (aTopic) {
+      case "nsPref:changed":
+        this._updateResetButton();
+        this._updateTitlebarButton();
+        this._updateUndoResetButton();
+        break;
+    }
+  },
+
+  _updateTitlebarButton: function() {
+    let drawInTitlebar = true;
+    try {
+      drawInTitlebar = Services.prefs.getBoolPref(kDrawInTitlebarPref);
+    } catch (ex) { }
+    let button = this.document.getElementById("customization-titlebar-visibility-button");
+    // Drawing in the titlebar means 'hiding' the titlebar:
+    if (drawInTitlebar) {
+      button.removeAttribute("checked");
+    } else {
+      button.setAttribute("checked", "true");
+    }
+  },
+
+  toggleTitlebar: function(aShouldShowTitlebar) {
+    // Drawing in the titlebar means not showing the titlebar, hence the negation:
+    Services.prefs.setBoolPref(kDrawInTitlebarPref, !aShouldShowTitlebar);
+  },
+#endif
+
+  _onDragStart: function(aEvent) {
+    __dumpDragData(aEvent);
+    let item = aEvent.target;
+    while (item && item.localName != "toolbarpaletteitem") {
+      if (item.localName == "toolbar") {
+        return;
+      }
+      item = item.parentNode;
+    }
+
+    let draggedItem = item.firstChild;
+    let placeForItem = CustomizableUI.getPlaceForItem(item);
+    let isRemovable = placeForItem == "palette" ||
+                      CustomizableUI.isWidgetRemovable(draggedItem);
+    if (item.classList.contains(kPlaceholderClass) || !isRemovable) {
+      return;
+    }
+
+    let dt = aEvent.dataTransfer;
+    let documentId = aEvent.target.ownerDocument.documentElement.id;
+    let isInToolbar = placeForItem == "toolbar";
+
+    dt.mozSetDataAt(kDragDataTypePrefix + documentId, draggedItem.id, 0);
+    dt.effectAllowed = "move";
+
+    let itemRect = draggedItem.getBoundingClientRect();
+    let itemCenter = {x: itemRect.left + itemRect.width / 2,
+                      y: itemRect.top + itemRect.height / 2};
+    this._dragOffset = {x: aEvent.clientX - itemCenter.x,
+                        y: aEvent.clientY - itemCenter.y};
+
+    gDraggingInToolbars = new Set();
+
+    // Hack needed so that the dragimage will still show the
+    // item as it appeared before it was hidden.
+    this._initializeDragAfterMove = function() {
+      // For automated tests, we sometimes start exiting customization mode
+      // before this fires, which leaves us with placeholders inserted after
+      // we've exited. So we need to check that we are indeed customizing.
+      if (this._customizing && !this._transitioning) {
+        item.hidden = true;
+        this._showPanelCustomizationPlaceholders();
+        DragPositionManager.start(this.window);
+        if (item.nextSibling) {
+          this._setDragActive(item.nextSibling, "before", draggedItem.id, isInToolbar);
+          this._dragOverItem = item.nextSibling;
+        } else if (isInToolbar && item.previousSibling) {
+          this._setDragActive(item.previousSibling, "after", draggedItem.id, isInToolbar);
+          this._dragOverItem = item.previousSibling;
+        }
+      }
+      this._initializeDragAfterMove = null;
+      this.window.clearTimeout(this._dragInitializeTimeout);
+    }.bind(this);
+    this._dragInitializeTimeout = this.window.setTimeout(this._initializeDragAfterMove, 0);
+  },
+
+  _onDragOver: function(aEvent) {
+    if (this._isUnwantedDragDrop(aEvent)) {
+      return;
+    }
+    if (this._initializeDragAfterMove) {
+      this._initializeDragAfterMove();
+    }
+
+    __dumpDragData(aEvent);
+
+    let document = aEvent.target.ownerDocument;
+    let documentId = document.documentElement.id;
+    if (!aEvent.dataTransfer.mozTypesAt(0)) {
+      return;
+    }
+
+    let draggedItemId =
+      aEvent.dataTransfer.mozGetDataAt(kDragDataTypePrefix + documentId, 0);
+    let draggedWrapper = document.getElementById("wrapper-" + draggedItemId);
+    let targetArea = this._getCustomizableParent(aEvent.currentTarget);
+    let originArea = this._getCustomizableParent(draggedWrapper);
+
+    // Do nothing if the target or origin are not customizable.
+    if (!targetArea || !originArea) {
+      return;
+    }
+
+    // Do nothing if the widget is not allowed to be removed.
+    if (targetArea.id == kPaletteId &&
+       !CustomizableUI.isWidgetRemovable(draggedItemId)) {
+      return;
+    }
+
+    // Do nothing if the widget is not allowed to move to the target area.
+    if (targetArea.id != kPaletteId &&
+        !CustomizableUI.canWidgetMoveToArea(draggedItemId, targetArea.id)) {
+      return;
+    }
+
+    let targetIsToolbar = CustomizableUI.getAreaType(targetArea.id) == "toolbar";
+    let targetNode = this._getDragOverNode(aEvent, targetArea, targetIsToolbar, draggedItemId);
+
+    // We need to determine the place that the widget is being dropped in
+    // the target.
+    let dragOverItem, dragValue;
+    if (targetNode == targetArea.customizationTarget) {
+      // We'll assume if the user is dragging directly over the target, that
+      // they're attempting to append a child to that target.
+      dragOverItem = (targetIsToolbar ? this._findVisiblePreviousSiblingNode(targetNode.lastChild) :
+                                        targetNode.lastChild) || targetNode;
+      dragValue = "after";
+    } else {
+      let targetParent = targetNode.parentNode;
+      let position = Array.indexOf(targetParent.children, targetNode);
+      if (position == -1) {
+        dragOverItem = targetIsToolbar ? this._findVisiblePreviousSiblingNode(targetNode.lastChild) :
+                                         targetParent.lastChild;
+        dragValue = "after";
+      } else {
+        dragOverItem = targetParent.children[position];
+        if (!targetIsToolbar) {
+          dragValue = "before";
+        } else {
+          dragOverItem = this._findVisiblePreviousSiblingNode(targetParent.children[position]);
+          // Check if the aDraggedItem is hovered past the first half of dragOverItem
+          let window = dragOverItem.ownerDocument.defaultView;
+          let direction = window.getComputedStyle(dragOverItem, null).direction;
+          let itemRect = dragOverItem.getBoundingClientRect();
+          let dropTargetCenter = itemRect.left + (itemRect.width / 2);
+          let existingDir = dragOverItem.getAttribute("dragover");
+          if ((existingDir == "before") == (direction == "ltr")) {
+            dropTargetCenter += (parseInt(dragOverItem.style.borderLeftWidth) || 0) / 2;
+          } else {
+            dropTargetCenter -= (parseInt(dragOverItem.style.borderRightWidth) || 0) / 2;
+          }
+          let before = direction == "ltr" ? aEvent.clientX < dropTargetCenter : aEvent.clientX > dropTargetCenter;
+          dragValue = before ? "before" : "after";
+        }
+      }
+    }
+
+    if (this._dragOverItem && dragOverItem != this._dragOverItem) {
+      this._cancelDragActive(this._dragOverItem, dragOverItem);
+    }
+
+    if (dragOverItem != this._dragOverItem || dragValue != dragOverItem.getAttribute("dragover")) {
+      if (dragOverItem != targetArea.customizationTarget) {
+        this._setDragActive(dragOverItem, dragValue, draggedItemId, targetIsToolbar);
+      } else if (targetIsToolbar) {
+        this._updateToolbarCustomizationOutline(this.window, targetArea);
+      }
+      this._dragOverItem = dragOverItem;
+    }
+
+    aEvent.preventDefault();
+    aEvent.stopPropagation();
+  },
+
+  _onDragDrop: function(aEvent) {
+    if (this._isUnwantedDragDrop(aEvent)) {
+      return;
+    }
+
+    __dumpDragData(aEvent);
+    this._initializeDragAfterMove = null;
+    this.window.clearTimeout(this._dragInitializeTimeout);
+
+    let targetArea = this._getCustomizableParent(aEvent.currentTarget);
+    let document = aEvent.target.ownerDocument;
+    let documentId = document.documentElement.id;
+    let draggedItemId =
+      aEvent.dataTransfer.mozGetDataAt(kDragDataTypePrefix + documentId, 0);
+    let draggedWrapper = document.getElementById("wrapper-" + draggedItemId);
+    let originArea = this._getCustomizableParent(draggedWrapper);
+    if (this._dragSizeMap) {
+      this._dragSizeMap.clear();
+    }
+    // Do nothing if the target area or origin area are not customizable.
+    if (!targetArea || !originArea) {
+      return;
+    }
+    let targetNode = this._dragOverItem;
+    let dropDir = targetNode.getAttribute("dragover");
+    // Need to insert *after* this node if we promised the user that:
+    if (targetNode != targetArea && dropDir == "after") {
+      if (targetNode.nextSibling) {
+        targetNode = targetNode.nextSibling;
+      } else {
+        targetNode = targetArea;
+      }
+    }
+    // If the target node is a placeholder, get its sibling as the real target.
+    while (targetNode.classList.contains(kPlaceholderClass) && targetNode.nextSibling) {
+      targetNode = targetNode.nextSibling;
+    }
+    if (targetNode.tagName == "toolbarpaletteitem") {
+      targetNode = targetNode.firstChild;
+    }
+
+    this._cancelDragActive(this._dragOverItem, null, true);
+    this._removePanelCustomizationPlaceholders();
+
+    try {
+      this._applyDrop(aEvent, targetArea, originArea, draggedItemId, targetNode);
+    } catch (ex) {
+      ERROR(ex, ex.stack);
+    }
+
+    this._showPanelCustomizationPlaceholders();
+  },
+
+  _applyDrop: function(aEvent, aTargetArea, aOriginArea, aDraggedItemId, aTargetNode) {
+    let document = aEvent.target.ownerDocument;
+    let draggedItem = document.getElementById(aDraggedItemId);
+    draggedItem.hidden = false;
+    draggedItem.removeAttribute("mousedown");
+
+    // Do nothing if the target was dropped onto itself (ie, no change in area
+    // or position).
+    if (draggedItem == aTargetNode) {
+      return;
+    }
+
+    // Is the target area the customization palette?
+    if (aTargetArea.id == kPaletteId) {
+      // Did we drag from outside the palette?
+      if (aOriginArea.id !== kPaletteId) {
+        if (!CustomizableUI.isWidgetRemovable(aDraggedItemId)) {
+          return;
+        }
+
+        CustomizableUI.removeWidgetFromArea(aDraggedItemId);
+        BrowserUITelemetry.countCustomizationEvent("remove");
+        // Special widgets are removed outright, we can return here:
+        if (CustomizableUI.isSpecialWidget(aDraggedItemId)) {
+          return;
+        }
+      }
+      draggedItem = draggedItem.parentNode;
+
+      // If the target node is the palette itself, just append
+      if (aTargetNode == this.visiblePalette) {
+        this.visiblePalette.appendChild(draggedItem);
+      } else {
+        // The items in the palette are wrapped, so we need the target node's parent here:
+        this.visiblePalette.insertBefore(draggedItem, aTargetNode.parentNode);
+      }
+      if (aOriginArea.id !== kPaletteId) {
+        // The dragend event already fires when the item moves within the palette.
+        this._onDragEnd(aEvent);
+      }
+      return;
+    }
+
+    if (!CustomizableUI.canWidgetMoveToArea(aDraggedItemId, aTargetArea.id)) {
+      return;
+    }
+
+    // Skipintoolbarset items won't really be moved:
+    if (draggedItem.getAttribute("skipintoolbarset") == "true") {
+      // These items should never leave their area:
+      if (aTargetArea != aOriginArea) {
+        return;
+      }
+      let place = draggedItem.parentNode.getAttribute("place");
+      this.unwrapToolbarItem(draggedItem.parentNode);
+      if (aTargetNode == aTargetArea.customizationTarget) {
+        aTargetArea.customizationTarget.appendChild(draggedItem);
+      } else {
+        this.unwrapToolbarItem(aTargetNode.parentNode);
+        aTargetArea.customizationTarget.insertBefore(draggedItem, aTargetNode);
+        this.wrapToolbarItem(aTargetNode, place);
+      }
+      this.wrapToolbarItem(draggedItem, place);
+      BrowserUITelemetry.countCustomizationEvent("move");
+      return;
+    }
+
+    // Is the target the customization area itself? If so, we just add the
+    // widget to the end of the area.
+    if (aTargetNode == aTargetArea.customizationTarget) {
+      CustomizableUI.addWidgetToArea(aDraggedItemId, aTargetArea.id);
+      // For the purposes of BrowserUITelemetry, we consider both moving a widget
+      // within the same area, and adding a widget from one area to another area
+      // as a "move". An "add" is only when we move an item from the palette into
+      // an area.
+      let custEventType = aOriginArea.id == kPaletteId ? "add" : "move";
+      BrowserUITelemetry.countCustomizationEvent(custEventType);
+      this._onDragEnd(aEvent);
+      return;
+    }
+
+    // We need to determine the place that the widget is being dropped in
+    // the target.
+    let placement;
+    let itemForPlacement = aTargetNode;
+    // Skip the skipintoolbarset items when determining the place of the item:
+    while (itemForPlacement && itemForPlacement.getAttribute("skipintoolbarset") == "true" &&
+           itemForPlacement.parentNode &&
+           itemForPlacement.parentNode.nodeName == "toolbarpaletteitem") {
+      itemForPlacement = itemForPlacement.parentNode.nextSibling;
+      if (itemForPlacement && itemForPlacement.nodeName == "toolbarpaletteitem") {
+        itemForPlacement = itemForPlacement.firstChild;
+      }
+    }
+    if (itemForPlacement && !itemForPlacement.classList.contains(kPlaceholderClass)) {
+      let targetNodeId = (itemForPlacement.nodeName == "toolbarpaletteitem") ?
+                            itemForPlacement.firstChild && itemForPlacement.firstChild.id :
+                            itemForPlacement.id;
+      placement = CustomizableUI.getPlacementOfWidget(targetNodeId);
+    }
+    if (!placement) {
+      LOG("Could not get a position for " + aTargetNode.nodeName + "#" + aTargetNode.id + "." + aTargetNode.className);
+    }
+    let position = placement ? placement.position : null;
+
+    // Is the target area the same as the origin? Since we've already handled
+    // the possibility that the target is the customization palette, we know
+    // that the widget is moving within a customizable area.
+    if (aTargetArea == aOriginArea) {
+      CustomizableUI.moveWidgetWithinArea(aDraggedItemId, position);
+    } else {
+      CustomizableUI.addWidgetToArea(aDraggedItemId, aTargetArea.id, position);
+    }
+
+    this._onDragEnd(aEvent);
+
+    // For BrowserUITelemetry, an "add" is only when we move an item from the palette
+    // into an area. Otherwise, it's a move.
+    let custEventType = aOriginArea.id == kPaletteId ? "add" : "move";
+    BrowserUITelemetry.countCustomizationEvent(custEventType);
+
+    // If we dropped onto a skipintoolbarset item, manually correct the drop location:
+    if (aTargetNode != itemForPlacement) {
+      let draggedWrapper = draggedItem.parentNode;
+      let container = draggedWrapper.parentNode;
+      container.insertBefore(draggedWrapper, aTargetNode.parentNode);
+    }
+  },
+
+  _onDragExit: function(aEvent) {
+    if (this._isUnwantedDragDrop(aEvent)) {
+      return;
+    }
+
+    __dumpDragData(aEvent);
+
+    // When leaving customization areas, cancel the drag on the last dragover item
+    // We've attached the listener to areas, so aEvent.currentTarget will be the area.
+    // We don't care about dragexit events fired on descendants of the area,
+    // so we check that the event's target is the same as the area to which the listener
+    // was attached.
+    if (this._dragOverItem && aEvent.target == aEvent.currentTarget) {
+      this._cancelDragActive(this._dragOverItem);
+      this._dragOverItem = null;
+    }
+  },
+
+  /**
+   * To workaround bug 460801 we manually forward the drop event here when dragend wouldn't be fired.
+   */
+  _onDragEnd: function(aEvent) {
+    if (this._isUnwantedDragDrop(aEvent)) {
+      return;
+    }
+    this._initializeDragAfterMove = null;
+    this.window.clearTimeout(this._dragInitializeTimeout);
+    __dumpDragData(aEvent, "_onDragEnd");
+
+    let document = aEvent.target.ownerDocument;
+    document.documentElement.removeAttribute("customizing-movingItem");
+
+    let documentId = document.documentElement.id;
+    if (!aEvent.dataTransfer.mozTypesAt(0)) {
+      return;
+    }
+
+    let draggedItemId =
+      aEvent.dataTransfer.mozGetDataAt(kDragDataTypePrefix + documentId, 0);
+
+    let draggedWrapper = document.getElementById("wrapper-" + draggedItemId);
+    draggedWrapper.hidden = false;
+    draggedWrapper.removeAttribute("mousedown");
+    if (this._dragOverItem) {
+      this._cancelDragActive(this._dragOverItem);
+      this._dragOverItem = null;
+    }
+    this._updateToolbarCustomizationOutline(this.window);
+    this._showPanelCustomizationPlaceholders();
+    DragPositionManager.stop();
+  },
+
+  _isUnwantedDragDrop: function(aEvent) {
+    // The simulated events generated by synthesizeDragStart/synthesizeDrop in
+    // mochitests are used only for testing whether the right data is being put
+    // into the dataTransfer. Neither cause a real drop to occur, so they don't
+    // set the source node. There isn't a means of testing real drag and drops,
+    // so this pref skips the check but it should only be set by test code.
+    if (this._skipSourceNodeCheck) {
+      return false;
+    }
+
+    /* Discard drag events that originated from a separate window to
+       prevent content->chrome privilege escalations. */
+    let mozSourceNode = aEvent.dataTransfer.mozSourceNode;
+    // mozSourceNode is null in the dragStart event handler or if
+    // the drag event originated in an external application.
+    return !mozSourceNode ||
+           mozSourceNode.ownerDocument.defaultView != this.window;
+  },
+
+  _setDragActive: function(aItem, aValue, aDraggedItemId, aInToolbar) {
+    if (!aItem) {
+      return;
+    }
+
+    if (aItem.getAttribute("dragover") != aValue) {
+      aItem.setAttribute("dragover", aValue);
+
+      let window = aItem.ownerDocument.defaultView;
+      let draggedItem = window.document.getElementById(aDraggedItemId);
+      if (!aInToolbar) {
+        this._setGridDragActive(aItem, draggedItem, aValue);
+      } else {
+        let targetArea = this._getCustomizableParent(aItem);
+        this._updateToolbarCustomizationOutline(window, targetArea);
+        let makeSpaceImmediately = false;
+        if (!gDraggingInToolbars.has(targetArea.id)) {
+          gDraggingInToolbars.add(targetArea.id);
+          let draggedWrapper = this.document.getElementById("wrapper-" + aDraggedItemId);
+          let originArea = this._getCustomizableParent(draggedWrapper);
+          makeSpaceImmediately = originArea == targetArea;
+        }
+        // Calculate width of the item when it'd be dropped in this position
+        let width = this._getDragItemSize(aItem, draggedItem).width;
+        let direction = window.getComputedStyle(aItem).direction;
+        let prop, otherProp;
+        // If we're inserting before in ltr, or after in rtl:
+        if ((aValue == "before") == (direction == "ltr")) {
+          prop = "borderLeftWidth";
+          otherProp = "border-right-width";
+        } else {
+          // otherwise:
+          prop = "borderRightWidth";
+          otherProp = "border-left-width";
+        }
+        if (makeSpaceImmediately) {
+          aItem.setAttribute("notransition", "true");
+        }
+        aItem.style[prop] = width + 'px';
+        aItem.style.removeProperty(otherProp);
+        if (makeSpaceImmediately) {
+          // Force a layout flush:
+          aItem.getBoundingClientRect();
+          aItem.removeAttribute("notransition");
+        }
+      }
+    }
+  },
+  _cancelDragActive: function(aItem, aNextItem, aNoTransition) {
+    this._updateToolbarCustomizationOutline(aItem.ownerDocument.defaultView);
+    let currentArea = this._getCustomizableParent(aItem);
+    if (!currentArea) {
+      return;
+    }
+    let isToolbar = CustomizableUI.getAreaType(currentArea.id) == "toolbar";
+    if (isToolbar) {
+      if (aNoTransition) {
+        aItem.setAttribute("notransition", "true");
+      }
+      aItem.removeAttribute("dragover");
+      // Remove both property values in the case that the end padding
+      // had been set.
+      aItem.style.removeProperty("border-left-width");
+      aItem.style.removeProperty("border-right-width");
+      if (aNoTransition) {
+        // Force a layout flush:
+        aItem.getBoundingClientRect();
+        aItem.removeAttribute("notransition");
+      }
+    } else  {
+      aItem.removeAttribute("dragover");
+      if (aNextItem) {
+        let nextArea = this._getCustomizableParent(aNextItem);
+        if (nextArea == currentArea) {
+          // No need to do anything if we're still dragging in this area:
+          return;
+        }
+      }
+      // Otherwise, clear everything out:
+      let positionManager = DragPositionManager.getManagerForArea(currentArea);
+      positionManager.clearPlaceholders(currentArea, aNoTransition);
+    }
+  },
+
+  _setGridDragActive: function(aDragOverNode, aDraggedItem, aValue) {
+    let targetArea = this._getCustomizableParent(aDragOverNode);
+    let draggedWrapper = this.document.getElementById("wrapper-" + aDraggedItem.id);
+    let originArea = this._getCustomizableParent(draggedWrapper);
+    let positionManager = DragPositionManager.getManagerForArea(targetArea);
+    let draggedSize = this._getDragItemSize(aDragOverNode, aDraggedItem);
+    let isWide = aDraggedItem.classList.contains(CustomizableUI.WIDE_PANEL_CLASS);
+    positionManager.insertPlaceholder(targetArea, aDragOverNode, isWide, draggedSize,
+                                      originArea == targetArea);
+  },
+
+  _getDragItemSize: function(aDragOverNode, aDraggedItem) {
+    // Cache it good, cache it real good.
+    if (!this._dragSizeMap)
+      this._dragSizeMap = new WeakMap();
+    if (!this._dragSizeMap.has(aDraggedItem))
+      this._dragSizeMap.set(aDraggedItem, new WeakMap());
+    let itemMap = this._dragSizeMap.get(aDraggedItem);
+    let targetArea = this._getCustomizableParent(aDragOverNode);
+    let currentArea = this._getCustomizableParent(aDraggedItem);
+    // Return the size for this target from cache, if it exists.
+    let size = itemMap.get(targetArea);
+    if (size)
+      return size;
+
+    // Calculate size of the item when it'd be dropped in this position.
+    let currentParent = aDraggedItem.parentNode;
+    let currentSibling = aDraggedItem.nextSibling;
+    const kAreaType = "cui-areatype";
+    let areaType, currentType;
+
+    if (targetArea != currentArea) {
+      // Move the widget temporarily next to the placeholder.
+      aDragOverNode.parentNode.insertBefore(aDraggedItem, aDragOverNode);
+      // Update the node's areaType.
+      areaType = CustomizableUI.getAreaType(targetArea.id);
+      currentType = aDraggedItem.hasAttribute(kAreaType) &&
+                    aDraggedItem.getAttribute(kAreaType);
+      if (areaType)
+        aDraggedItem.setAttribute(kAreaType, areaType);
+      this.wrapToolbarItem(aDraggedItem, areaType || "palette");
+      CustomizableUI.onWidgetDrag(aDraggedItem.id, targetArea.id);
+    } else {
+      aDraggedItem.parentNode.hidden = false;
+    }
+
+    // Fetch the new size.
+    let rect = aDraggedItem.parentNode.getBoundingClientRect();
+    size = {width: rect.width, height: rect.height};
+    // Cache the found value of size for this target.
+    itemMap.set(targetArea, size);
+
+    if (targetArea != currentArea) {
+      this.unwrapToolbarItem(aDraggedItem.parentNode);
+      // Put the item back into its previous position.
+      currentParent.insertBefore(aDraggedItem, currentSibling);
+      // restore the areaType
+      if (areaType) {
+        if (currentType === false)
+          aDraggedItem.removeAttribute(kAreaType);
+        else
+          aDraggedItem.setAttribute(kAreaType, currentType);
+      }
+      this.createOrUpdateWrapper(aDraggedItem, null, true);
+      CustomizableUI.onWidgetDrag(aDraggedItem.id);
+    } else {
+      aDraggedItem.parentNode.hidden = true;
+    }
+    return size;
+  },
+
+  _getCustomizableParent: function(aElement) {
+    let areas = CustomizableUI.areas;
+    areas.push(kPaletteId);
+    while (aElement) {
+      if (areas.indexOf(aElement.id) != -1) {
+        return aElement;
+      }
+      aElement = aElement.parentNode;
+    }
+    return null;
+  },
+
+  _getDragOverNode: function(aEvent, aAreaElement, aInToolbar, aDraggedItemId) {
+    let expectedParent = aAreaElement.customizationTarget || aAreaElement;
+    // Our tests are stupid. Cope:
+    if (!aEvent.clientX  && !aEvent.clientY) {
+      return aEvent.target;
+    }
+    // Offset the drag event's position with the offset to the center of
+    // the thing we're dragging
+    let dragX = aEvent.clientX - this._dragOffset.x;
+    let dragY = aEvent.clientY - this._dragOffset.y;
+
+    // Ensure this is within the container
+    let boundsContainer = expectedParent;
+    // NB: because the panel UI itself is inside a scrolling container, we need
+    // to use the parent bounds (otherwise, if the panel UI is scrolled down,
+    // the numbers we get are in window coordinates which leads to various kinds
+    // of weirdness)
+    if (boundsContainer == this.panelUIContents) {
+      boundsContainer = boundsContainer.parentNode;
+    }
+    let bounds = boundsContainer.getBoundingClientRect();
+    dragX = Math.min(bounds.right, Math.max(dragX, bounds.left));
+    dragY = Math.min(bounds.bottom, Math.max(dragY, bounds.top));
+
+    let targetNode;
+    if (aInToolbar) {
+      targetNode = aAreaElement.ownerDocument.elementFromPoint(dragX, dragY);
+      while (targetNode && targetNode.parentNode != expectedParent) {
+        targetNode = targetNode.parentNode;
+      }
+    } else {
+      let positionManager = DragPositionManager.getManagerForArea(aAreaElement);
+      // Make it relative to the container:
+      dragX -= bounds.left;
+      // NB: but if we're in the panel UI, we need to use the actual panel
+      // contents instead of the scrolling container to determine our origin
+      // offset against:
+      if (expectedParent == this.panelUIContents) {
+        dragY -= this.panelUIContents.getBoundingClientRect().top;
+      } else {
+        dragY -= bounds.top;
+      }
+      // Find the closest node:
+      targetNode = positionManager.find(aAreaElement, dragX, dragY, aDraggedItemId);
+    }
+    return targetNode || aEvent.target;
+  },
+
+  _onMouseDown: function(aEvent) {
+    LOG("_onMouseDown");
+    if (aEvent.button != 0) {
+      return;
+    }
+    let doc = aEvent.target.ownerDocument;
+    doc.documentElement.setAttribute("customizing-movingItem", true);
+    let item = this._getWrapper(aEvent.target);
+    if (item && !item.classList.contains(kPlaceholderClass) &&
+        item.getAttribute("removable") == "true") {
+      item.setAttribute("mousedown", "true");
+    }
+  },
+
+  _onMouseUp: function(aEvent) {
+    LOG("_onMouseUp");
+    if (aEvent.button != 0) {
+      return;
+    }
+    let doc = aEvent.target.ownerDocument;
+    doc.documentElement.removeAttribute("customizing-movingItem");
+    let item = this._getWrapper(aEvent.target);
+    if (item) {
+      item.removeAttribute("mousedown");
+    }
+  },
+
+  _getWrapper: function(aElement) {
+    while (aElement && aElement.localName != "toolbarpaletteitem") {
+      if (aElement.localName == "toolbar")
+        return null;
+      aElement = aElement.parentNode;
+    }
+    return aElement;
+  },
+
+  _showPanelCustomizationPlaceholders: function() {
+    let doc = this.document;
+    let contents = this.panelUIContents;
+    let narrowItemsAfterWideItem = 0;
+    let node = contents.lastChild;
+    while (node && !node.classList.contains(CustomizableUI.WIDE_PANEL_CLASS) &&
+           (!node.firstChild || !node.firstChild.classList.contains(CustomizableUI.WIDE_PANEL_CLASS))) {
+      if (!node.hidden && !node.classList.contains(kPlaceholderClass)) {
+        narrowItemsAfterWideItem++;
+      }
+      node = node.previousSibling;
+    }
+
+    let orphanedItems = narrowItemsAfterWideItem % CustomizableUI.PANEL_COLUMN_COUNT;
+    let placeholders = CustomizableUI.PANEL_COLUMN_COUNT - orphanedItems;
+
+    let currentPlaceholderCount = contents.querySelectorAll("." + kPlaceholderClass).length;
+    if (placeholders > currentPlaceholderCount) {
+      while (placeholders-- > currentPlaceholderCount) {
+        let placeholder = doc.createElement("toolbarpaletteitem");
+        placeholder.classList.add(kPlaceholderClass);
+        //XXXjaws The toolbarbutton child here is only necessary to get
+        //  the styling right here.
+        let placeholderChild = doc.createElement("toolbarbutton");
+        placeholderChild.classList.add(kPlaceholderClass + "-child");
+        placeholder.appendChild(placeholderChild);
+        contents.appendChild(placeholder);
+      }
+    } else if (placeholders < currentPlaceholderCount) {
+      while (placeholders++ < currentPlaceholderCount) {
+        contents.querySelectorAll("." + kPlaceholderClass)[0].remove();
+      }
+    }
+  },
+
+  _removePanelCustomizationPlaceholders: function() {
+    let contents = this.panelUIContents;
+    let oldPlaceholders = contents.getElementsByClassName(kPlaceholderClass);
+    while (oldPlaceholders.length) {
+      contents.removeChild(oldPlaceholders[0]);
+    }
+  },
+
+  /**
+   * Update toolbar customization targets during drag events to add or remove
+   * outlines to indicate that an area is customizable.
+   *
+   * @param aWindow                       The XUL window in which outlines should be updated.
+   * @param {Element} [aToolbarArea=null] The element of the customizable toolbar area to add the
+   *                                      outline to. If aToolbarArea is falsy, the outline will be
+   *                                      removed from all toolbar areas.
+   */
+  _updateToolbarCustomizationOutline: function(aWindow, aToolbarArea = null) {
+    // Remove the attribute from existing customization targets
+    for (let area of CustomizableUI.areas) {
+      if (CustomizableUI.getAreaType(area) != CustomizableUI.TYPE_TOOLBAR) {
+        continue;
+      }
+      let target = CustomizableUI.getCustomizeTargetForArea(area, aWindow);
+      target.removeAttribute("customizing-dragovertarget");
+    }
+
+    // Now set the attribute on the desired target
+    if (aToolbarArea) {
+      if (CustomizableUI.getAreaType(aToolbarArea.id) != CustomizableUI.TYPE_TOOLBAR)
+        return;
+      let target = CustomizableUI.getCustomizeTargetForArea(aToolbarArea.id, aWindow);
+      target.setAttribute("customizing-dragovertarget", true);
+    }
+  },
+
+  _findVisiblePreviousSiblingNode: function(aReferenceNode) {
+    while (aReferenceNode &&
+           aReferenceNode.localName == "toolbarpaletteitem" &&
+           aReferenceNode.firstChild.hidden) {
+      aReferenceNode = aReferenceNode.previousSibling;
+    }
+    return aReferenceNode;
+  },
+};
+
+function __dumpDragData(aEvent, caller) {
+  if (!gDebug) {
+    return;
+  }
+  let str = "Dumping drag data (" + (caller ? caller + " in " : "") + "CustomizeMode.jsm) {\n";
+  str += "  type: " + aEvent["type"] + "\n";
+  for (let el of ["target", "currentTarget", "relatedTarget"]) {
+    if (aEvent[el]) {
+      str += "  " + el + ": " + aEvent[el] + "(localName=" + aEvent[el].localName + "; id=" + aEvent[el].id + ")\n";
+    }
+  }
+  for (let prop in aEvent.dataTransfer) {
+    if (typeof aEvent.dataTransfer[prop] != "function") {
+      str += "  dataTransfer[" + prop + "]: " + aEvent.dataTransfer[prop] + "\n";
+    }
+  }
+  str += "}";
+  LOG(str);
+}
+
+function dispatchFunction(aFunc) {
+  Services.tm.currentThread.dispatch(aFunc, Ci.nsIThread.DISPATCH_NORMAL);
+}