NotifyDatafield of the event message.
The string that you need to pass to this attribute must be formatted as follows: Name of the notification attribute, followed by a colon, followed by a user data string, followed by a semi-colon. The sequence may then be repeated as many times as it is requred.
For example: "Active: foo; DoubleClick: bar;". When the "Active" notification is triggered, "foo" will be send to the event handler callback. When the "DoubleClick" attribute triggers, "bar" will be sent.
See Notifications for details.