Flex4 DataGrid中如何嵌入RadioButton

<s:DataGrid id="viewDg" width="100%" height="100%" fontFamily="微软雅黑"
horizontalScrollPolicy="off" borderVisible="false"
dataProvider="{viewList}">
<s:columns>
<s:ArrayList>
<s:GridColumn width="{wid0.02}" resizable="false"
itemRenderer="Module_SchoolView.RadioButtonGridItemRenderer"/>


<s:GridColumn width="{wid0.25}" headerText="名称" dataField="xysj02" resizable="false"/>

<s:GridColumn width="{wid0.25}" headerText="地名" dataField="xysj02name" resizable="false"/>

<s:GridColumn width="{wid0.35}" headerText="URL" dataField="xysj04" resizable="false"/>

<s:GridColumn width="{wid0.13}" headerText="备注" dataField="xysj05" resizable="false"/>
</s:ArrayList>
</s:columns>
</s:DataGrid>

<?xml version="1.0" encoding="utf-8"?>
<s:GridItemRenderer xmlns:fx="http://ns.adobe./mxml/2009"
xmlns:s="library://ns.adobe./flex/spark"
xmlns:mx="library://ns.adobe./flex/mx">
<fx:Declarations>
<!-- 将非可视元素（例如服务、值对象）放在此处 -->
</fx:Declarations>
<fx:Script>
<![CDATA[

//----------------------------------------------------------------------------------------------------------

override public function prepare(hasBeenRecycled:Boolean):void
{
super.prepare( hasBeenRecycled );

// We make the radio button mimic the selection status of the whole row.
const selected_items: Vector.<Object> = grid.dataGrid.selectedItems;

if( null == selected_items )
{
radio_button.selected = false;
return;
}

if( -1 != selected_items.indexOf( data ) )
radio_button.selected = true;
else
radio_button.selected = false;
}

//----------------------------------------------------------------------------------------------------------

]]>
</fx:Script>

<!--The radio button is only a visual indicator for whether the row is selected or not.
The "selected" property of the radio_button will be controlled by the "prepare" function.
The radio_button should not be allowed any user interaction. Hence disabling it.-->
<s:RadioButton id="radio_button"
label=""
enabled="false"

horizontalCenter="0" verticalCenter="0" />

</s:GridItemRenderer>