For a long time we have had reports about drag&drop freezing the Windows desktop in Bauhaus on Windows.

Turns out that this is a known issue inside Qt:

From qwidget.cpp:

/* Works only as long as pointer is inside the application's window,
which is good enough for QDockWidget.

Doesn't call SetWindowsHookEx() - this function causes a system-wide
freeze if any other app on the system installs a hook and fails to
process events. */
void QWidgetPrivate::grabMouseWhileInWindow()
...

and e.g. qdockwidget.cpp then does

#ifdef Q_OS_WIN
          grabMouseWhileInWindow()
#else
          grabMouse()
#endif

Interestingly, e.g. widgets/resizehandler.cpp again uses grabMouse(), even on Windows, which probably might lead to freezes there too ...

We should allow customers (& QtCreator) to do the very same 'tricks' we do internally to avoid lock-ups, and expose grabMouseWhileInWindow(). I'd even go for making it the default behavior on Windows, since 'misbehaving' programs that causes these freezes seems to be very common.