[Xcb] Casting events.

[Jeremy Kolb]

RandR has a ScreenChangeNotifyEvent.  Now I have an XCBGenericEvent and 
when there's a ScreenChangeNotifyEvent I cast the XCBGenericEvent. 
However this results in a loss of information on certain fields.  Is 
there any other way to do this or am I doing it incorrectly?

	switch (event->response_type - event_base) {
	case XCBRandRScreenChangeNotify:
	  sce = (XCBRandRScreenChangeNotifyEvent *) &event;



Jeremy