Spark datagrid selection item (add/select without CTRL down)

Question

I would like to select items of a DataGrid (selectionMode="multipleRows") as if CTRL key was down. So I would like to select item if item wasn't selected or deselect item if it was.

I tryed using changing event and preventdefault but isn't working right.

Any ideas ?

Regards

trying this

        private function ev_selectionChanging(e:GridSelectionEvent):void {
            if (e.kind == 'setRow'){
                e.kind = 'addRow';
            }

            //e.preventDefault();
        }