Swing Menu is not repainting correctly after ALT+TAB & Move operations

I did a sequence of actions and I ended up opening 2 menus with my Swing application on WinXP. Do the following to reproduce the bug -

1. Run the attached sample test. A frame would come up
2. Press 'F10'. The first menu will drop-down.
3. Press ALT+TAB and choose the same java application.
4. Press ALT+SPACE BAR and choose MOVE option using arrow keys.
5. Press 'ENTER' key to mark the completion of move operation.
6. You will see that the 'File' menu opened would still be visible.

Now click on any of the other menus and you will see 2 menus being shown at the same time. This is reproducible only with Metal LAF on WinXP on JDK6+. Not reproducible on Tiger.

I have noticed another behavior with F10 which could be closely related to this -

1. Click on the text field.
2. Press F10. A menu is shown
3. Press ALT key once. Menu disappears and focus is restored back to TextField
4. Type any letter now. The typed letter would not be reflected on the text field. If you type it again, you will see it there. So the first key press is actually getting consumed somewhere.

This is also seen right from JDK6. I am not able to reproduce this on Tiger since ALT key does not make the menu disappear.