Paint bug and palette errors after some events in Windows

In a Windows widget application, the palette/painting gets corrupted after some desktop events, making the interface unreadable

It has been reported after:

• Waking up from sleep states on a laptop
• When connecting via Remote Desktop Protocol (RDP) with visual styles disabled

The issue may be reproduced easily:

Method 1 : RDP
1) Create an application with a QMainWindow.
In main(), set the fusion theme, set a stylesheet to

"QMainWindow { background: palette(base); }"

and set a dark theme QPalette. There is a minimal application example attached.

2) Connect to a Windows 7 Professional desktop via RDP, disabling the "Visual Styles" in Options / Experience. Using a Professional edition is maybe important as RDP Theming support varies between Windows versions.

3) Start the compiled application. It should appear dark gray. Disconnect leaving the application window open.

4) Reconnect via RDP still again "Visual Styles" disabled. The window should turn white, this is the bug.

Method 2 : Sleep state
Use the same application as in Method 1. Launch the application, the GUI appears as it should (dark theme, hello world readable in status bar). Put the computer on sleep state and wake up. The GUI is now fully white and the status bar is not readable (white on white)