protected override void OnLeave(EventArgs e)

Protected Overrides Sub OnLeave(e As EventArgs)

Raising an event invokes the event handler through a delegate.

The OnLeave method also allows derived classes to handle the event without attaching a delegate. This is the preferred technique for handling the event in a derived class.

Notes to Inheritors: When overriding OnLeave in a derived class, be sure to call the base class's OnLeave method so that registered delegates receive the event.