It's called events, and you don't use APi's to declare them, you use delcare them with Event:
Code:
Private WithEvents tb As TextBox
Public Event Keypress(KeyAscii As Integer)


Private Sub tb_KeyPress(KeyAscii As Integer)
    'To raise the event use raiseevent
    RaiseEvent Keypress(KeyAscii)
End Sub
This is an example how you can raise events with a class containing a textbox.