AFter upgrading a project from Flex4 Beta1 to Beta2, I've found that the background-image style is no longer supported on Halo components.
Eg:
<mx:VBox xmlns:mx="http://www.adobe.com/2006/mxml"
backgroundImage="@Embed(source='myImage.png')" />
Note that jira issue SDK-23050 points out the following :
backgroundImage is not supported for Spark skins.
But this is not using a spark skin, just a standard Halo component.
Anyone got any ideas?