diff -r 000000000000 -r 6474c204b198 browser/metro/base/content/flyoutpanels/FlyoutPanelsUI.js
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/browser/metro/base/content/flyoutpanels/FlyoutPanelsUI.js	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,120 @@
+// -*- Mode: js2; tab-width: 2; indent-tabs-mode: nil; js2-basic-offset: 2; js2-skip-preprocessor-directives: t; -*-
+/* 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';
+
+let FlyoutPanelsUI = {
+  _isInitialized: false,
+
+  init: function() {
+    if (this._isInitialized) {
+      Cu.reportError("Attempted to initialize FlyoutPanelsUI more than once");
+      return;
+    }
+
+    Cu.import("resource://gre/modules/XPCOMUtils.jsm");
+    Cu.import("resource://gre/modules/Services.jsm");
+
+    this._isInitialized = true;
+    let scriptContexts = {};
+    let scripts =
+          [
+            ['AboutFlyoutPanel', 'chrome://browser/content/flyoutpanels/AboutFlyoutPanel.js'],
+            ['PrefsFlyoutPanel', 'chrome://browser/content/flyoutpanels/PrefsFlyoutPanel.js'],
+            ['SearchFlyoutPanel', 'chrome://browser/content/flyoutpanels/SearchFlyoutPanel.js'],
+#ifdef MOZ_SERVICES_SYNC
+            ['SyncFlyoutPanel', 'chrome://browser/content/flyoutpanels/SyncFlyoutPanel.js'],
+#endif
+          ];
+
+    scripts.forEach(function (aScript) {
+      let [name, script] = aScript;
+      XPCOMUtils.defineLazyGetter(FlyoutPanelsUI, name, function() {
+        let sandbox = {};
+        Services.scriptloader.loadSubScript(script, sandbox);
+        sandbox[name].init();
+        return sandbox[name];
+      });
+    });
+
+    Services.obs.addObserver(this, "metro_viewstate_changed", false);
+    window.addEventListener("TabOpen", this, false);
+  },
+
+  uninit: function () {
+    Services.obs.removeObserver(this, "metro_viewstate_changed");
+    window.removeEventListener("TabOpen", this, false);
+  },
+
+  show: function(aToShow) {
+    if (!this[aToShow]) {
+      throw("FlyoutPanelsUI asked to show '" + aToShow + "' which does not exist");
+    }
+
+    if (this._currentFlyout) {
+      if (this._currentFlyout == this[aToShow]) {
+        return;
+      } else {
+        this.hide();
+      }
+    }
+
+    this._currentFlyout = this[aToShow];
+    if (this._currentFlyout._show) {
+      this._currentFlyout._show();
+    } else {
+      this._currentFlyout._topmostElement.show();
+    }
+    DialogUI.pushPopup(this, this._currentFlyout._topmostElement);
+  },
+
+  onBackButton: function() {
+    if (this._currentFlyout._onBackButton) {
+      this._currentFlyout._onBackButton();
+    } else {
+      this.hide();
+      Services.metro.showSettingsFlyout();
+    }
+  },
+
+  get isVisible() {
+    return this._currentFlyout ? true : false;
+  },
+
+  handleEvent: function (aEvent) {
+    switch (aEvent.type) {
+      case "TabOpen":
+        this.hide()
+        break;
+    }
+  },
+
+  observe: function (aSubject, aTopic, aData) {
+    switch (aTopic) {
+      case "metro_viewstate_changed":
+        if (aData == "snapped") {
+          this.hide();
+        }
+        break;
+    }
+  },
+
+  dispatchEvent: function(aEvent) {
+    if (this._currentFlyout) {
+      this._currentFlyout._topmostElement.dispatchEvent(aEvent);
+    }
+  },
+
+  hide: function() {
+    if (this._currentFlyout) {
+      if (this._currentFlyout._hide) {
+        this._currentFlyout._hide();
+      } else {
+        this._currentFlyout._topmostElement.hide();
+      }
+      DialogUI.popPopup(this);
+      delete this._currentFlyout;
+    }
+  }
+};