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void QObject::installEventFilter ( QObject * filterObj )
Installs an event filter filterObj on this object. For example:
     monitoredObj->installEventFilter(filterObj);
An event filter is an object that receives all events that are sent to this object. The filter can either stop the event or forward it to this object. The event filter filterObj receives events via its eventFilter() function. The eventFilter() function must return true if the event should be filtered, (i.e. stopped); otherwise it must return false.

setAttribute(Qt::WA_TransparentForMouseEvents);

bool CMyApp::notify ( QObject * receiver, QEvent * event ) 
{
	if (receiver->inherits("CShadowWidget")) // сообщение пришло тени
	{
		if (event->type() == QEvent::MouseMove)  // и по ней двигается мышка
		{
			QPoint p = ((QMouseEvent*)event)->globalPos();
			QWidget* newReceiver = widgetAt(p); // найдём того, кто лежит под тенью
			if (newReceiver) // а таки лежит
			{
				((QWidget*)receiver)->setCursor(newReceiver->cursor()); // поставим на тени курсор от ниже лежащего
				receiver = newReceiver; // переправим событие нижележащему
			}
		}
	}
	return QApplication::notify(receiver,event);
}