[aivashchenko]

получилось добавить кнопку:

datagrid.getColumnAt(3).cellRenderer=MyRenderer2

MyRenderer2.as

package
{
 
	import fl.controls.CheckBox;
	import fl.controls.DataGrid;
	import fl.controls.ComboBox;
    import fl.controls.Button;
    import fl.controls.listClasses.ICellRenderer;
    import fl.controls.listClasses.ListData;
  import fl.containers.BaseScrollPane;
	import flash.events.MouseEvent;
 
    public class MyRenderer2 extends Button implements ICellRenderer {
        private var _listData:ListData;
        private var _data:Object;
 
        public function MyRenderer2() {
 	this.addEventListener(MouseEvent.CLICK, mouseClickHandler);
        }
 
  private function mouseClickHandler(e:MouseEvent):void {
       _data.Number;
    }
 
 
        public function set listData(newListData:ListData):void {
             _listData = newListData;  
             //-------------------------------
  	label = "TEST";  //--запишем в кнопку значение
     }
 
        public function get listData():ListData {
            return _listData;
        }
 
        public function set data(newData:Object):void {
            _data = newData;
        }
 
        public function get data():Object {
           return _data;
        }
    }
}

но ComboBox не добавляет...