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NAME

       XtAddEventHandler, XtAddRawEventHandler, XtRemoveEventHandler,
       XtRemoveRawEventHandler, XtInsertEventHandler, XtInsertRawEventHandler
       - add and remove event handlers

SYNTAX

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

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

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

       void XtInsertRawEventHandler(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 (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
       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