NAME

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

SYNTAX

       #include <X11/Intrinsic.h>

       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(Display* display, 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(3)
       X Toolkit Intrinsics - C Language Interface
       Xlib - C Language X Interface