Hiding MainWindow on macOS 10.6 freezes the GUI

I’ve encountered a very strange problem on my MacBook Pro which is running macOS 10.6.8. When hiding a simple application with a MainWindow and a text field (by hitting CMD – H, or going to the top menu and pressing Hide MyApp) the GUI freezes. I have to minimize and maximize it (button on the MainWindow) to get the GUI to become responsive again.

What I did to get this behavior was simply create a new project in QT (5.2.1) Widget Application with a MainWindow drag a QLineEdit inside the form then build it. I then deploy it using: /Users/maharajah/Qt/5.2.1/clang_64/bin/macdeployqt MyApp.app

Update:
To reproduce this you can just use the "Application Example" that comes with Qt build it in release and run /Users/maharajah/Qt/5.2.1/clang_64/bin/macdeployqt ApplicationExample.app

Then move it over to macOS 10.6.8 and use CMD - H and then click in dock. The GUI will now be frozen.