Public Class Form1
    Declare Auto Function SendMessage Lib "user32" (hWnd As IntPtr, wMsg As _
      Int32, _
                                      wParam As Int32, lParam As Int32) As Int32
    Dim WithEvents Btn1 As New Button With {.Dock = DockStyle.Bottom, .Text = _
      "Start", .Parent = Me}
    Const WM_SYSCOMMAND As Int32 = &H112&
    Const SC_SCREENSAVE As Int32 = &HF140&
 
    Private Sub Btn1_MouseDown(sender As Object, e As MouseEventArgs) Handles _
      Btn1.MouseDown
        SendMessage(Me.Handle, WM_SYSCOMMAND, SC_SCREENSAVE, 0) 'Ein
        Threading.Thread.Sleep(3000)                    '3 Sek Pause
        SendKeys.Send("Keys.Space")                            ' Aus
    End Sub
End Class