rem: handler->eventMask = mask;
add: handler->eventMask = eventMask;
context: WMCreateEventHandler(WMView *view, unsigned long mask, WMEventProc *eventProc,		     void *clientData){    W_EventHandler *handler;    W_EventHandler *ptr = view->handlerList;    unsigned long eventMask;            if (ptr==NULL) {	handler = wmalloc(sizeof(W_EventHandler));	handler->nextHandler = NULL;		view->handlerList = handler;		eventMask = mask;    } else {	handler = NULL;	eventMask = mask;	while (ptr != NULL) {	    if (ptr->clientData == clientData && ptr->proc == eventProc) {		handler = ptr;	    }	    	    eventMask |= ptr->eventMask;	    	    ptr = ptr->nextHandler;	}	if (!handler) {	    handler = wmalloc(sizeof(W_EventHandler));	    handler->nextHandler = view->handlerList;	    view->handlerList = handler;	}	    }    /* select events for window */    handler->eventMask = mask;    handler->proc = eventProc;    handler->clientData = clientData;}