Windows startup/shutdown

Kode 

Imports Microsoft.Win32

Public Class Form1
    Private Shared WM_QUERYENDSESSION As Integer = &H11
    Private Shared systemShutdown As Boolean = False

    Protected Overrides Sub WndProc(ByRef m As System.Windows.Forms.Message)

        If m.Msg = WM_QUERYENDSESSION Then
            MessageBox.Show("queryendsession: this is a logoff, shutdown, or reboot")
            systemShutdown = True
        End If

        ' If this is WM_QUERYENDSESSION, the closing event should be raised in the base WndProc.
        MyBase.WndProc(m)

    End Sub 'WndProc 

    Private Sub Form1_Closing(ByVal sender As System.Object, ByVal e As System.ComponentModel.CancelEventArgs) Handles MyBase.Closing

        If (systemShutdown) Then
            ' Reset the variable because the user might cancel the shutdown.
            systemShutdown = False

            If (DialogResult.Yes = _
                    MessageBox.Show("My application", "Do you want to save your work before logging off?", MessageBoxButtons.YesNo)) Then
                e.Cancel = True

            Else
                e.Cancel = False

            End If

        End If

    End Sub

End Class