wrong windowState() if the window state is changed through MS Windows taskbar

The windowState() is not updated when the window is minimized using the "Show desktop" button, or "Cascade windows" taskbar menu item.

1. Maximise a qmainwindow
2. Ms windows xp taskbar-> cascade
3. the window is restored
i) windowState() still says window is maximised
ii) QEvent::WindowStateChange is not sent