[Development] Qt 5 Mac losing window focus/active state

[Stephen Chu]

I am having a lot of issue with window active state (or focus?) on Mac. 
In addition to losing focus after clicking a combo box, I ran into this one:
<https://bugreports.qt-project.org/browse/QTBUG-27198>

Basically after clicking at a empty window, clicking at the zoom button 
and after the the window is maximized, the window title becomes inactive 
although the window content is still getting clicks.

I tried to find out the cause of this but couldn't get anywhere. :(