Consider the following:

1. Press on an enabled menu item in a menu bar.
2. While keeping the mouse button pressed, move the mouse to a disabled menu item in the menu bar.
3. While keeping the mouse button pressed, move the mouse back to the enabled menu item.

Expected result:

When the mouse moves back to the enabled menu item, its menu should be shown.

Actual result:

When the mouse moves back to the enabled menu item, its menu is not shown.

If the mouse button is released, the menus of the enabled menu items show up when the mouse moves over them, until the mouse moves over the disabled menu item again, or the mouse button is clicked.

This is a regression from Qt 4.1.