code: function(isInstant) {
        if (this._lastDragOp) {
          this._lastDragOp.clean && this._lastDragOp.clean(isInstant);
          this._lastDragOp.deregister && this._lastDragOp.deregister();
          this._lastDragOp = null;
        }
      }
docs: Clear any active drag effects on the list.