Qt::WindowStaysOnTopHint causes weird transparent partial window

[ce_nort]

I have a Mainwindow that opens up a child window (inherits QMainwindow as well) when a button is clicked. I was having issues with the parent window popping back on top of the child window in certain situations, so in the constructor of the child window I put

this->setWindowFlags(Qt::WindowStaysOnTopHint);

this->setWindowFlags(Qt::WindowStaysOnTopHint);

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. But now when I try to open the child window, it is a weird transparent half-window that is only visible where it overlaps with the parent window. The best way to describe how it looks is a glitch: Screen Shot 2016-03-31 at 10.36.23 AM.png Any idea what is going on here or how to fix it?