ListItemRenderer background color

Question

Using flex4, I have a list with an item renderer:

<mx:List id="queueView" dataProvider="{presenter.queue.items}">
  <mx:itemRenderer>
    <fx:Component>
      <mx:VBox>
        <mx:Label text="{data.name}"/>
        <mx:Label text="{data.artist.name}"/>
      </mx:VBox>
    </fx:Component>
  </mx:itemRenderer>
</mx:List>

I have alternating colors on the list:

#queueView
{
  alternating-item-colors: red, yellow;
}

but the list items always render with a white background (it renders the colors correctly if I get rid of the renderer).

If I set contentBackgroundColor="red" on the itemRenderer every item is red. The compiler won't accept transparent.

How can I make the itemRenderer respect the alternating colors of the list?