Button's context menu appears in wrong position in Full Screen mode on Windows

Button's context menu appears offscreen in Full Screen mode.

Steps to reproduce:
1) Please build and run attached example.
2) Enter Full Screen mode (press Fullscreen button)
3) Click on menu button in any place. Context menu will partially hiden (offscreen)

Related bug: https://bugreports.qt.io/browse/QTBUG-48858

Please note that this is regression in Qt 5.5.0. Everything works fine in Qt 5.4.1.