flex DataGrid 表头分组

<mx:AdvancedDataGrid 
					 width="2000"
					 height="100%">
	<mx:groupedColumns>
		<mx:AdvancedDataGridColumnGroup headerText="医学观察"
												textAlign="center">
			<mx:AdvancedDataGridColumn headerText="{'开始\n日期'}"
									   width="80"
									   editable="true"
									   dataField="medFollowStart"
									   labelFunction="dateFormatStart"
									   textAlign="center"
									   itemRenderer="mx.controls.Label"/>
			<mx:AdvancedDataGridColumn headerText="{'解除\n日期'}"
									   textAlign="center"
									   width="80"
									   dataField="medFollowEnd"
									   labelFunction="dateFormatEnd"
									   editable="true"
									   itemRenderer="mx.controls.Label"/>
		</mx:AdvancedDataGridColumnGroup>
	</mx:groupedColumns>
</mx:AdvancedDataGrid>