docs: function (cbName, propName, propNewVal) {
              var cb = this._cfg[cbName];
              var cancelDefault = false;
              if (cb) {
                  var params = {
                      cancelDefault : true
                  };
                  this.evalCallback(cb, params);
                  cancelDefault = params.cancelDefault;
              }
              if (!cancelDefault) {
                  this.changeProperty(propName, propNewVal);
              }
          }