docs: function locationBar_getElement(spec) {
      var elem = null;
  
      switch(spec.type) {
        /**
         * subtype: subtype to match
         * value: value to match
         */
        case "contextMenu":
          elem = new elementslib.Lookup(this._controller.window.document, CONTEXT_MENU);
          break;
        case "contextMenu_entry":
          elem = new elementslib.Lookup(this._controller.window.document, CONTEXT_MENU +
                                        '/{"cmd":"cmd_' + spec.subtype + '"}');
          break;
        case "favicon":
          elem = new elementslib.ID(this._controller.window.document, "page-proxy-favicon");
          break;
        case "feedButton":
          elem = new elementslib.ID(this._controller.window.document, "feed-button");
          break;
        case "goButton":
          elem = new elementslib.ID(this._controller.window.document, "urlbar-go-button");
          break;
        case "historyDropMarker":
          elem = new elementslib.Lookup(this._controller.window.document,
                                        URLBAR_CONTAINER + '/id("urlbar")/anon({"anonid":"historydropmarker"})');
          break;
        case "identityBox":
          elem = new elementslib.ID(this._controller.window.document, "identity-box");
          break;
        case "notification_element":
          elem = new elementslib.Lookup(this._controller.window.document, NOTIFICATION_POPUP +
                                        spec.subtype);
          break;
        case "notification_popup":
          elem = new elementslib.Lookup(this._controller.window.document, NOTIFICATION_POPUP);
          break;
        case "starButton":
          elem = new elementslib.ID(this._controller.window.document, "star-button");
          break;
        case "urlbar":
          elem = new elementslib.ID(this._controller.window.document, "urlbar");
          break;
        case "urlbar_input":
          elem = new elementslib.Lookup(this._controller.window.document, URLBAR_INPUTBOX +
                                        '/anon({"anonid":"input"})');
          break;
        default:
          throw new Error(arguments.callee.name + ": Unknown element type - " + spec.type);
      }
  
      return elem;
    }