Private Sub frmMain_FormClosing(ByVal sender As Object, ByVal e As _
      System.Windows.Forms.FormClosingEventArgs) Handles Me.FormClosing
        If e.CloseReason <> CloseReason.WindowsShutDown Then
            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 If
    End Sub