QML fullscreen application on Windows 7 keeps rendering minimizing switching to other windows

I have a QML application that runs fullscreen on windows 7 not quite as expected.

When using mesa (just putting precompiled opengl32.dll near the executable file), everything renders normally.

When compiling Qt using ANGLE it also works fine.

But when using native opengl:
a) Qt quick comboboxes are not rendered (when clicking, looks like the main window is rendered over the combobox items). Same thing with system dialogs (open file/save file, etc), they just don't appear.
b) when switching apps with alt+tab, the switch seems to occur, all mouse\keyboard events go the the other window, BUT qml application is still rendered on top of everything

All other non-qml opengl applications work normally. Also I tested my app on another computer with an nvidia geforce 430 and it works well.