Can't focus on custom itemRenderer?

Question

I have made a custom itemRenderer doubling as an itemEditor
following the guidelines in the documentation.
However, even though I have set the rendererIsEditor="true",
when tabbing amongst other editable fields, the controls inside the
itemRenderer do not receive focus. I can't help but think this is
an oversight/bug but is there any way to jury-rig the itemRenderer
to focus properly? At the moment my component is simply a CheckBox
inside an HBox.
Anyway, here is my code so you can see for yourself (I have
included a CheckBox as itemRenderer so you can see the *desired*
effect.
<?xml version="1.0" encoding="utf-8"?>
<mx:Application
xmlns:mx="
http://www.adobe.com/2006/mxml"
layout="vertical">
<mx:Script>
<![CDATA[
import mx.controls.dataGridClasses.DataGridListData;
import mx.controls.Alert;
[Bindable]
public var dp:Array = [{num:2, bool:true}, {num:3,
bool:false}];
]]>
</mx:Script>
<mx:DataGrid id="test" editable="true"
dataProvider="{dp}">
<mx:columns>
<mx:DataGridColumn dataField="num" headerText="num" />
<mx:DataGridColumn dataField="bool"
headerText="Sent"
itemRenderer="mx.controls.CheckBox"
rendererIsEditor="true" editorDataField="selected" />
<mx:DataGridColumn dataField="num" headerText="num"
editable="true" />
<mx:DataGridColumn dataField="bool" headerText="Sent"
rendererIsEditor="true" editorDataField="blorch">
<mx:itemRenderer>
<mx:Component>
<mx:HBox horizontalAlign="center">
<mx:Boolean id="blorch" />
<mx:CheckBox id="check" selected="{data.bool}"
change="blorch=check.selected" />
</mx:HBox>
</mx:Component>
</mx:itemRenderer>
</mx:DataGridColumn>
<mx:DataGridColumn dataField="num" headerText="num"
editable="true" />
</mx:columns>
</mx:DataGrid>
</mx:Application>

Answer 1

nevermind... I found the answer a few pages later in the
docs...
you have to implement the IFocusManagerComponent interface
and then override drawFocus as below to set the focus on the
checkBox... hope it works for multiple controls...
<mx:HBox horizontalAlign="center"
backgroundColor="#9933EE"
implements="mx.managers.IFocusManagerComponent">
<mx:Script>
<![CDATA[
override public function drawFocus(focused:Boolean):void {
check.setFocus();
]]>
</mx:Script>
<mx:Boolean id="blorch" />
<mx:CheckBox id="check" selected="{data.bool}"
change="blorch=check.selected"
updateComplete="blorch=check.selected" />
</mx:HBox>