MousePress event which closes a popupWidget passed to another widget

Steps to reproduce:
1. Open any kind of popupWidget (e.g. a Menu) which should grab the mouse
2. Click outside the popup to close the popupWidget preferable on another widget
3. Widget under cursor reacts to the mouse event

This is a regression in comparison to Qt 4.8.

Attached is a small QTest which illustrates the issue. It uses XTest to simulate the problem. There are two .pro files, one for qt4 and one for qt5. The test succeeds for Qt4, but fails for qt5.