- add and remove event handlers

SYNTAX

       void XtAddEventHandler(Widget w, EventMask event_mask, Boolean nonmask-
              able, XtEventHandler proc, XtPointer client_data);

       void XtAddRawEventHandler(Widget w, EventMask event_mask, Boolean non-
              maskable, XtEventHandler proc, XtPointer client_data);

       void XtRemoveEventHandler(Widget w, EventMask event_mask, Boolean non-
              maskable, XtEventHandler proc, XtPointer client_data);

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

       void XtInsertEventHandler(Widget w, EventMask event_mask, Boolean non-
              maskable, XtEventHandler proc, XtPointer client_data, XtListPo-
              sition position);

       void XtInsertRawEventHandler(Widget w, EventMask event_mask, Boolean
              nonmaskable, XtEventHandler proc, XtPointer client_data, XtList-
              Position 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 proce-
                 dure should be called or removed on the nonmaskable events
                 (GraphicsExpose, NoExpose, SelectionClear, SelectionRequest,
                 SelectionNotify, 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

       XtInsertEventHandler is identical to XtAddEventHandler with the addi-
       tional 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 XtList-
       Tail, 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 XSelect-
       Input for the specified events. If the procedure is already registered
       with the same client_data value, the specified mask augments the exist-
       ing 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



X Version 11                      Release 6.6           XtAddEventHandler(3Xt)