docs: function () {
              var errorTipPosition = this._WidgetCfg.errorTipPosition;
              var preferredPositions = [this._preferredPositions[errorTipPosition]];
              for (var i in this._preferredPositions) {
                  if (this._preferredPositions.hasOwnProperty(i) && errorTipPosition != i) {
                      preferredPositions.push(this._preferredPositions[i]);
                  }
              }
              return preferredPositions;
          }