docs: function(event, cb) {
              if (this._cfg.waiAria) {
                  var field = this.getTextInputField();
                  var listWidget = this.controller.getListWidget();
                  var ariaActiveDescendant = listWidget ? listWidget.getSelectedOptionDomId() : null;
                  if (ariaActiveDescendant != null) {
                      field.setAttribute("aria-activedescendant", ariaActiveDescendant);
                  } else {
                      field.removeAttribute("aria-activedescendant");
                  }
              }
              if (cb) {
                  this.$callback(cb, event);
              }
          }