docs: function softwareUpdate_getElement(spec) {
      var elem = null;
  
      switch(spec.type) {
        /**
         * subtype: subtype to match
         * value: value to match
         */
        case "button":
          elem = new elementslib.Lookup(this._controller.window.document,
                                        WIZARD_BUTTONS_BOX + WIZARD_BUTTON[spec.subtype]);
          break;
        case "wizard":
          elem = new elementslib.Lookup(this._controller.window.document, WIZARD);
          break;
        case "wizard_page":
          elem = new elementslib.Lookup(this._controller.window.document, WIZARD_DECK +
                                        '/id(' + spec.subtype + ')');
          break;
        case "download_progress":
          elem = new elementslib.ID(this._controller.window.document, "downloadProgress");
          break;
        default:
          throw new Error(arguments.callee.name + ": Unknown element type - " + spec.type);
      }
  
      return elem;
    }