Declare Function CallWindowProc Lib "user32.dll" _
  Alias "CallWindowProcA" ( _
  ByVal lpPrevWndFunc As Long, _
  ByVal hWnd As Long, _
  ByVal Msg As Long, _
  ByVal WParam As Long, _
  ByVal lParam As Long) As Long
 
    Declare Function FindWindow Lib "user32.dll" _
  Alias "FindWindowA" ( _
  ByVal lpClassName As String, _
  ByVal lpWindowName As String) As Long
 
    Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As _
      System.EventArgs) Handles Button1.Click
        Dim WM_QUERYENDSESSION As Integer = &H11
        Dim hwnd As Long
        'Für Testzwecke wird der name der aktuellen Form benutzt
        hwnd = FindWindow(Me.Name, vbNullString)
        Dim x As Long = CallWindowProc(0, hwnd, WM_QUERYENDSESSION, 0, 0)
        If x <> 0 Then
            MsgBox("")
        End If
    End Sub
 
    Protected Overrides Sub WndProc(ByRef m As System.Windows.Forms.Message)
        Dim WM_QUERYENDSESSION As Integer = &H11
        If m.Msg = WM_QUERYENDSESSION Then
            MsgBox("Close")
            Me.Close()
        End If
        MyBase.WndProc(m)
    End Sub