Public Sub AddWindowToCallbackList(ByVal CallbackDelegate As _
  UserChangedDelegate)
  UserChangedCallbackList.Add(CallbackDelegate)
End Sub

Public Sub RemoveWindowFromCallbackList(ByVal CallbackDelegate As _
  UserChangedDelegate)
  For Each del As UserChangedDelegate In UserChangedCallbackList
    If del.Target Is CallbackDelegate.Target Then
      UserChangedCallbackList.Remove(del)
      Exit For 'Eintrag gefunden, Schleife verlassen
    End If
  Next
End Sub