Main Menu items do not close when clicking on them

Steps:
1- Open MuseScore;
2- Click on File menu; the menu opens;
3- Click again on "File".

Expected result: the menu closes.
Actual result: the menu is still open.

Windows 8, commit b53a32163

This is another regression due to the switch to Qt 5.1, it works as expected with an old Qt 4.8 build.