Control Exiting Event Handler Delegate
public delegate void ContentControlExitingEventHandler(object sender, ContentControlExitingEventArgs e);
The source of the event.
The data for the event.
When you create a ContentControlExitingEventHandler delegate, you identify the method that will handle the event. To associate the event with your event handler, add an instance of the delegate to the event. The event handler is called whenever the event occurs, unless you remove the delegate.