protected virtual void OnTextChanging(object sender, TextChangingEventArgs e)

Protected Overridable Sub OnTextChanging(sender As Object, e As TextChangingEventArgs)

Raising an event invokes the event handler through a delegate.

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