Private Sub DoFormClosing(ByVal sender As System.Object, ByVal e As            _
                          System.ComponentModel.CancelEventArgs) Handles _
   MyBase.Closing  
           If MessageBox.Show("Wollen Sie das Fenster schließen?", "Fenster" & _
           "schließen", MessageBoxButtons.YesNo, MessageBoxIcon.Question) = _
           DialogResult.Yes Then  
               e.Cancel = False  
            Else  
                e.Cancel = True  
            End If  
    End Sub