protected override void OnPopUpOpening(PopUpOpeningEventArgs e)

Protected Overrides Sub OnPopUpOpening(e As PopUpOpeningEventArgs)

Raising an event invokes the event handler through a delegate.

The OnPopUpOpening 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 OnPopUpOpening in a derived class, be sure to call the base class's OnPopUpOpening method so that registered delegates receive the event.