X11: QMenu options in application that uses multiple screens can be selected on screen they are not showing

QMenu seem to be receiving events even from screens they are not visible on. When opening widgets on 2 screens and one has QMenu active, options can be selected from the other screen by clicking on the same relative position.

To reproduce:
1. make sure you have multiple screens in your setup (see Xephyr)
2. launch application, open one of the menus
3. click on the other screen on same position as menu item on the first screen
-> text should change in the first screen

It is possible to test this with Xephyr:
Xephyr -screen 500x400 -screen 500x400 :2 &
DISPLAY=:2 ./app