Windows 7 themed owner-drawn combo box

Hello all -

I have an owner-drawn combo box class where I provide background colors for items in a combo box. When an item is selected, the background color of the edit portion of the combo box reflects the selected color. In a themed Windows 7, the combo boxes look as attached. I was looking at using the theming API to draw the combo box in this way, but couldn't figure out how to do it, given the available parts and states for a combo box. Does anyone have any ideas? Thanks!

- Steve