[Development] Print Screen does not work with Qt context menus

[Ilya Fedin]

> They do not seem to close or dismiss the menu. They capture that fine
> for Print Screen. My guess would be that they pass the event back to
> the operating system and/or windowing manager. I do not know whether
> Qt or a Qt application could easily do the same.

I just tried to press PrtSc while having an open context menu in
Firefox and it's closed as soon as I pressed the key, Spectacle created
a screenshot without the menu