Sub Buchung(ByVal Betrag As Decimal)
        If Betrag + m_Kontostand < m_Dispo Then
            Dim Abbrechen As Boolean
            RaiseEvent DispoGrenze(Me, Abbrechen)
            If Abbrechen Then Exit Sub
        End If
        m_Kontostand = Math.Max(m_Kontostand + Betrag, m_Dispo)
    End Sub

    Private Sub x_DispoGrenze(sender As Object, _
        ByRef Abbrechen As Boolean) Handles x.DispoGrenze
 
        Abbrechen = MsgBox("Dispo überschritten - Restbetrag abbuchen?", _
                MsgBoxStyle.YesNo) = MsgBoxResult.No
 
    End Sub