visual anomaly: menu stays in "onMouseOver" visual state

See the attached image. The `bar' menu acts as if the cursor is hovering over it, even though it isn't anymore.

Steps to reproduce:
1) Run the testcase.
2) Click the `foo' menu, and leave the cursor at its position.
3) Hover over the `bar' menu, and leave the cursor at its position.
4) Move downwards, into the client space of the window, so that the cursor
is not anymore hovering over the menu or its items.
5) Left click once to dismiss the menu.
6) Hover over the `foo' or `bar' menu, and leave the cursor at its position.
7) Repeat step 4 and 5.
8) Observe that the menu you hovered over in step 6 is still in its
"onMouseOver" state. It looks as if the cursor is still hovering over the
menu, even though it is not.

NOTE:
Whether the bug is reproducible might depend on the theme. A default Windows XP or Unix-like + KDE4 installation with the Oxygen style should work.

Other:
I've observed this bug since at least Qt 4.6.3 (haven't tested earlier versions).