PIT:REG: Choice takes a couple of clicks to select an item, Vista

I have a frame with a Choice. When I click on the choice, the drop-down appears. Now when I rollover the mouse on the choice items, I expect the items to be highlighted when I move the mouse. But I see that the focus border shifts to the new item when the mouse moves and the item is not highlighted. I need to click the item 2 times to select it. This happens only the first time after the top-level gains focus and becomes active. After that it works fine. However, when I click on some other window and come back to the frame containing choice, it happens again.

I reproduced it with 6u10-b26 PIT build on Windows Vista Home Premium. Not reproducible on 6u10-b25. Not reproducible on WinXP with PIT build. Hence it is a PIT bug and a regression introduced in b26.

To reproduce the bug, run the attached test. You will see a frame, window and a dialog each having a choice. Click on the choice and try to select an item. you will see the above behavior. Try on all the top-levels.