In this section we discuss the notifications at the client side.
A DOM event (Event) is the DOM-level (i.e., low-level) event that is usually triggered by the browser. It is usually listened by the implementation of a widget, rather than the client application.
A widget event is the high-level event. It is used either to encapsulate a DOM event, or to represent a notification specific to a widget, or to an application.
It is generally suggested to listen widget events (rather than DOM events) if possible, since it is easier and more efficient.
A client activity watch is a notification for special activities that are not available as DOM events or widget events, for example, the notification when a widget is becoming invisible.