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NAME

       XtInsertEventTypeHandler, XtRemoveEventTypeHandler,
       XtRegisterExtensionSelector, XtSetEventDispatcher,
       XtDispatchEventToWidget - extension event handling

SYNTAX

       void XtInsertEventTypeHandler(Widget widget, int event_type, XtPointer
              select_data, XtEventHandler proc, XtPointer client_data,
              XtListPosition position);

       void XtRemoveEventTypeHandler(Widget widget, int event_type, XtPointer
              select_data, XtEventHandler proc, XtPointer client_data);

       void XtRegisterExtensionSelector(Display* display, int min_event_type,
              int max_event_type, XtExtensionSelectProc proc, XtPointer
              client_data);

       XtEventDispatchProc XtSetEventDispatcher(Widget widget, int event_type,
              XtEventDispatchProc proc);

       Boolean XtDispatchEventToWidget(Widget widget, XEvent* event);

ARGUMENTS

       widget    Specifies the widget for this event handler.  Must be of
                 class Core or any subclass thereof.

       event_type
                 Specifies the event type.

       select_data
                 Specifies data used to select or deselect events from the
                 server.

       proc      Specifies the proc.

       client_data
                 Specifies additional data to be passed to the event handler.

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

       display   Specifies the display.

       min_event_type, max_event_type
                 Specifies the range of event types for this extension.

       event     Specifies a pointer to the event to be dispatched.

DESCRIPTION

       The XtInsertEventTypeHandler function registers a procedure with the
       dispatch mechanism that is to be called when an event that matches the
       specified event_type is dispatched to the specified widget.

       If event_type is one of the core X protocol events then select_data
       must be a pointer to a value of type EventMask, indicating the event
       mask to be used to select for the desired event.  This event mask will
       be included in the value returned by XtBuildEventMask.  If the widget
       is realized XtInsertEventTypeHandler calls XSelectInput if necessary.
       Specifying NULL for select_data is equivalent to specifying a pointer
       to an event mask containing 0. This is similar to the
       XtInsertRawEventHandler function.

       If event_type specifies an extension event type then the semantics of
       the data pointed to by select_data are defined by the extension
       selector registered for the specified event type.

       In either case the Intrinsics are not required to copy the data pointed
       to by select_data, so the caller must ensure that it remains valid as
       long as the event handler remains registered with this value of
       select_data.

       The position argument allows the client to control the order of the
       invocation of event handlers registered for the same event type. If the
       client does not care about the order, it should normally specify
       XtListTail, which registers this event handler after any previously
       registered handlers for this event type.

       The XtRemoveEventTypeHandler function unregisters an even handler
       registered with XtInsertEventTypeHandler for the specified event type.
       The request is ignored if client_data does not match the value given
       with the handler was registered.

       If event_type specifies on of the core X protocol events, select_data
       must be a pointer to a value of type EventMask, indicating the mask to
       be used to deselect for the appropriate event.  If the widget is
       realized, XtRemoveEventTypeHandler calls XSelectInput if necessary.
       Specifying NULL for select_data is equivalent to specifying a pointer
       to an event mask containing 0. This is similar to the
       XtRemoveRawEventHandler function.

       If event_type specifies an extension event type then the semantics of
       the data pointed to by select_data are defined by the extension
       selector registered for the specified event type.

       The XtRegisterExtensionSelector function registers a procedure to
       arrange for the delivery of extension events to widgets.

       If min_event_type and max_event_type match the parameters to a previous
       call to XtRegisterExtensionSelector for the same display, the proc and
       client_data replace the previously registered values. If the range
       specified by min_event_type and max_event_type overlaps the range of
       the parameters to a previous call for the same display in any other
       way, an error results.

       The XtSetEventDispatcher function registers the event dispatcher
       procedure specified by proc for events with the type event_type. The
       previously registered dispatcher (or the default dispatcher if there
       was no previously registered dispatcher) is returned. If proc is NULL,
       the default procedure is restored for the specified type.

       In the future, when XtDispatchEvent is called with an event of
       event_type, the specified proc (or the default dispatcher) will be
       invoked to determine a widget ot which to dispatch the event.

       The XtDispatchEventToWidget function scans the list of registered event
       handlers for the specified widget and calls each handler that has been
       registered for the specified event type, subject to the
       continue_to_dispatch value returned by each handler. The Intrinsics
       behave as if event handlers were registered at the head of the list for
       Expose, NoExpose, GraphicsExpose, and VisibilityNotify events to invoke
       the widget’s expose procedure according to the exposure compression
       rules and to update the widget’s visible field if visible_interest is
       True.  These internal event handlers never set continue_to_dispatch to
       False.

       XtDispatchEventToWidget returns True if any event handler was called
       and False otherwise.

SEE ALSO

       XtGetKeyboardFocusWidget(3Xt)
       X Toolkit Intrinsics - C Language Interface
       Xlib - C Language X Interface