More On Events

Some of the event routines have conditional versions. They take a routine of this form which returns true if the event is wanted, else False.

  Bool (*predicate)(display,event,args)
  Display *display;
  XEvent *event;
  char *args;

XIfEvent(display,event,predicate,args) /* returns an event iff right sort*/
   Display *display;
   XEvent *event;
   Bool (*predicate)();
   char *args;

XCheckIfEvent(display,event,predicate,args) 
   Display *display;
   XEvent *event;
   Bool (*predicate)();
   char *args;

XPeekIfEvent(display,event,predicate,args)  /* conditional Peek */
   Display *display;   
   XEvent *event;      
   Bool (*predicate)();
   char *args;