QApplication::keyboardModifiers not updated when dragging window

If you start dragging a window (say a floating QDockWidget) and then press and hold say the Control key, QApplication::keyboardModifiers() indicates the Control key is not held down when it is. Because of this, I can't check if the Control key is held down by checking QApplication::keyboardModifiers() and updating the allowed docking areas to prevent docking if the Control key is held down.