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XtAddEventHandler(3Xt)		XT FUNCTIONS	       XtAddEventHandler(3Xt)



NAME
  XtAddEventHandler, XtAddRawEventHandler, XtRemoveEventHandler, XtRemoveRaw-
  EventHandler, XtInsertEventHandler, XtInsertRawEventHandler - add and
  remove event handlers

SYNTAX
  void XtAddEventHandler(w, event_mask, nonmaskable, proc, client_data)
	Widget w;
	EventMask event_mask;
	Boolean nonmaskable;
	XtEventHandler proc;
	XtPointer client_data;

  void XtAddRawEventHandler(w, event_mask, nonmaskable, proc, client_data)
	Widget w;
	EventMask event_mask;
	Boolean nonmaskable;
	XtEventHandler proc;
	XtPointer client_data;

  void XtRemoveEventHandler(w, event_mask, nonmaskable, proc, client_data)
	Widget w;
	EventMask event_mask;
	Boolean nonmaskable;
	XtEventHandler proc;
	XtPointer client_data;

  void XtRemoveRawEventHandler(w, event_mask, nonmaskable, proc, client_data)
	Widget w;
	EventMask event_mask;
	Boolean nonmaskable;
	XtEventHandler proc;
	XtPointer client_data;

  void XtInsertEventHandler(w, event_mask, nonmaskable, proc, client_data,
  position)
	Widget w;
	EventMask event_mask;
	Boolean nonmaskable;
	XtEventHandler proc;
	XtPointer client_data;
	XtListPosition position;

  void XtInsertRawEventHandler(w, event_mask, nonmaskable, proc, client_data,
  position)
	Widget w;
	EventMask event_mask;
	Boolean nonmaskable;
	XtEventHandler proc;
	XtPointer client_data;
	XtListPosition position;


  typedef enum { XtListHead, XtListTail } XtListPosition;

ARGUMENTS

  client_data
	    Specifies additional data to be passed to the client's event
	    handler.

  event_mask
	    Specifies the event mask for which to call or unregister this
	    procedure.

  nonmaskable
	    Specifies a Boolean value that indicates whether this procedure
	    should be called or removed on the nonmaskable events (Gra-
	    phicsExpose, NoExpose, SelectionClear, SelectionRequest, Selec-
	    tionNotify, ClientMessage, and MappingNotify).

  proc	    Specifies the procedure that is to be added or removed.

  w	    Specifies the widget for which this event handler is being
	    registered.

  position  Specifies when the event handler is to be called relative to
	    other previously registered handlers.

DESCRIPTION
  The XtAddEventHandler function registers a procedure with the dispatch
  mechanism that is to be called when an event that matches the mask occurs
  on the specified widget.  If the procedure is already registered with the
  same client_data, the specified mask is ORed into the existing mask.	If
  the widget is realized, XtAddEventHandler calls XSelectInput, if necessary.

  The XtAddRawEventHandler function is similar to XtAddEventHandler except
  that it does not affect the widget's mask and never causes an XSelectInput
  for its events.  Note that the widget might already have those mask bits
  set because of other nonraw event handlers registered on it.

  The XtRemoveRawEventHandler function stops the specified procedure from
  receiving the specified events.  Because the procedure is a raw event
  handler, this does not affect the widget's mask and never causes a call on
  XSelectInput.

  XtInsertEventHandler is identical to XtAddEventHandler with the additional
  position argument. if position is XtListHead, the event handler is
  registered to that it will be called before any event handlers that were
  previously registered for the same widget.  If position is XtListTail, the
  event handler is registered to be called after any previously registered
  event handlers. If the procedure is already registered with the same
  client_data value, the specified mask augments the existing mask and the
  procedure is repositioned in the list.

  XtInsertRawEventHandler is similar to XtInsertEventHandler except that it
  does not modify the widget's event mask and never causes an XSelectInput
  for the specified events. If the procedure is already registered with the
  same client_data value, the specified mask augments the existing mask and
  the procedure is repositioned in the list.

SEE ALSO
  XtAppNextEvent(3Xt), XtBuildEventMask(3Xt)
  X Toolkit Intrinsics - C Language Interface
  Xlib - C Language X Interface










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