Receiving System Notifications

A system notification occurs when an event is triggered with an event type less than User_Base_Event (16). Non‑GUI objects (that is, objects that are not instances of a Window subclass) respond to system notifications by implementing the Object class sysNotification method.

GUI objects (that is, objects that are instances of a Window subclass) respond to system notifications by implementing their Window subclass sysNotify event method.

The sysNotification method has the following signature.

sysNotification(eventType: Integer;
                theObject: Object;
                eventTag:  Integer) updating, abstract;

The sysNotify method has the following signature.

sysNotify([control:  Control-type input;] // parameter only for controls
          eventType: Integer;
          theObject: Object;
          eventTag:  Integer) updating;

For examples of the sysNotification and sysNotify methods, see "System Notification Examples", later in this section.