Transparent Widget does not redraw properly when using extendFrameIntoClientArea

I've been using extendFrameIntoClientArea to have a complete semi-transparent widget on Windows but I figure out that in Qt 5 (just moved from Qt 4.8 with my own custom function to Qt 5.3.1), widgets doesn't redraw properly, I have issue with QLabel but also QTabWidget.

In the case of QLabel, using clear() function or setText() doesn't work properly, the text is written on top and the label not redraw before resized.
I attached a sample project that show the glitch behavior on Windows 7.

In the case of QTabWidget, removing closable tabs still draw it even it's not here anymore, resizing the window will fix the drawing.

If you need anymore information, please ask.