Public Class Form1
    Dim WithEvents Btn1 As New Button With {.Dock = DockStyle.Bottom, .Text = _
      "Start", .Parent = Me}
    Dim WithEvents T As New Timer With {.Interval = 3000} '3 Sekunden
    Declare Auto Function SendMessage Lib "user32" (ByVal hWnd As IntPtr, ByVal _
      wMsg As Int32, ByVal wParam As Int32, ByVal lParam As Int32) As Int32
 
    Const WM_SYSCOMMAND As Int32 = &H112&
    Const SC_SCREENSAVE As Int32 = &HF140&
 
    Private Sub Btn1_MouseDown(ByVal sender As Object, ByVal e As _
      MouseEventArgs) Handles Btn1.MouseDown
        SendMessage(Me.Handle, WM_SYSCOMMAND, SC_SCREENSAVE, 0) 'Ein
        T.Start()
    End Sub
 
    Private Sub T_Tick(sender As Object, e As System.EventArgs) Handles T.Tick
        SendKeys.Send("Keys.Space")                       ' Nach 3 Sek. Aus
        T.Stop()
    End Sub
End Class