hpux man page for xcheckmaskevent

XCheckMaskEvent()														 XCheckMaskEvent()

Name
  XCheckMaskEvent - remove the next event that matches mask; don't wait.

Synopsis
  Bool XCheckMaskEvent(display, event_mask, event_return)
	Display *display;
	long event_mask;
	XEvent *event_return;

Arguments
  display   Specifies a connection to an X server; returned from XOpenDisplay().

  event_mask
	    Specifies the event types to be returned.  See list under XSelectInput().

  event_return
	    Returns a copy of the matched event's XEvent structure.

Returns
  True if a matching event is found, else False.

Description
  XCheckMaskEvent()  removes  the  next  event in the queue that matches the passed mask.  The event is copied into an XEvent supplied by the
  caller and XCheckMaskEvent() returns True.  Other events earlier in the queue are not discarded.  If no such event has been queued, XCheck-
  MaskEvent() flushes the request buffer and immediately returns False, without waiting.

  XCheckMaskEvent()  cannot  return  ClientMessage,  MappingNotify, SelectionClear, SelectionNotify, or SelectionRequest events because these
  event types are by definition unmaskable.

  For more information, see Volume One, Chapter 8, Events.

See Also
  XQLength(), XAllowEvents(), XCheckIfEvent(), XCheckTypedEvent(), XCheckTypedWindowEvent(), XCheckWindowEvent(), XEventsQueued(), XGetInput-
  Focus(),  XGetMotionEvents(), XIfEvent(), XMaskEvent(), XNextEvent(), XPeekEvent(), XPeekIfEvent(), XPending(), XPutBackEvent(), XSelectIn-
  put(), XSendEvent(), XSetInputFocus(), XSynchronize(), XWindowEvent().

Xlib - Input Handling														 XCheckMaskEvent()