retrieve a widget's event mask
- EventMask XtBuildEventMask(Widget w);
Specifies the widget.
function returns the event mask representing the logical OR
of all event masks for event handlers registered on the widget with
and all event translations, including accelerators,
installed on the widget.
This is the same event mask stored into the
and sent to the server when event handlers and translations are installed or
removed on the realized widget.