<?xml version="1.0" encoding="utf-8"?>
<mx:Canvas xmlns:mx="http://www.adobe.com/2006/mxml"
    implements="mx.controls.listClasses.IDropInListItemRenderer"
    creationComplete="onComplete()">
    
    <mx:Script>
        <![CDATA[
            import mx.events.CollectionEvent;
            import mx.controls.dataGridClasses.DataGridListData;
            import mx.collections.ArrayCollection;
            import mx.controls.DataGrid;
            import mx.controls.dataGridClasses.DataGridColumn;
            import mx.controls.listClasses.BaseListData;
            
            private var _listData:BaseListData;
            private var _dataGrid:DataGrid;
            private var _dataField:String;
            [Bindable] private var _CBselected:Boolean;
            [Bindable] private var _headerLabel:String;
            
            private function onComplete():void {
                cb.setStyle("fontWeight", this.getStyle("fontWeight"));
            }
            
            [Bindable("dataChange")]
            public function get listData():BaseListData
            {
                return _listData;
            }
        
            public function set listData(value:BaseListData):void
            {
                _listData = value;
                //_dataGrid = value.owner as DataGrid;
                _dataField = (value as DataGridListData).dataField;
                _headerLabel = value.label;
            }
            
            override public function set data(value:Object):void {
                super.data = value;
                
                var column:DataGridColumn = value as DataGridColumn;
                column.sortable = false;
                
                checkForSelectedItems();
            }
            
            private function checkForSelectedItems():void {
                var dp:ArrayCollection = _dataGrid.dataProvider as ArrayCollection;
                var n:Number = 0;
                for(var i:int=0 ; i < dp.length ; i++){
                    if(dp[i][_dataField])
                        n++
                }
                if(n == dp.length){
                    _CBselected = true;
                }
            }
            
            private function onCBchange(event:Event):void {
                var dp:ArrayCollection = _dataGrid.dataProvider as ArrayCollection;
                
                for(var i:int=0 ; i < dp.length ; i++){
                    dp[i][_dataField] = cb.selected;
                }
                _dataGrid.invalidateList();
            }
            
        ]]>
    </mx:Script>
    <mx:CheckBox id="cb" horizontalCenter="0" useHandCursor="true" buttonMode="true"
        change="onCBchange(event)" selected="{_CBselected}" />
</mx:Canvas>

<?xml version="1.0" encoding="utf-8"?>
<mx:Canvas top="0" xmlns:mx="http://www.adobe.com/2006/mxml" 
    implements="mx.controls.listClasses.IDropInListItemRenderer">
    <mx:Script>
        <![CDATA[
            import mx.events.CollectionEvent;
            import mx.collections.ArrayCollection;
            import mx.controls.dataGridClasses.DataGridListData;
            import mx.controls.DataGrid;
            import mx.controls.listClasses.BaseListData;
            
            private var _listData:BaseListData;
            private var _dataGrid:DataGrid;
            private var _dataField:String;
            
            
            [Bindable("dataChange")]
            public function get listData():BaseListData
            {
                return _listData;
            }
            public function set listData(value:BaseListData):void {
                _listData = value;
                _dataGrid = value.owner as DataGrid;
                _dataField = (value as DataGridListData).dataField;
            }
            
            override public function set data(value:Object):void {
                super.data = value;
                cb.selected = value[_dataField];
            }
            
            private function onChange():void {
                data[_dataField] = cb.selected;
                var dp:ArrayCollection = _dataGrid.dataProvider as ArrayCollection;
                dp.dispatchEvent(new CollectionEvent(CollectionEvent.COLLECTION_CHANGE));
            }
        ]]>
    </mx:Script>
    <mx:CheckBox paddingTop="2" paddingBottom="10" id="cb" horizontalCenter="0" change="onChange()" />
</mx:Canvas>