Load WPF app in a specific screen point

private void Application_Startup(object sender, StartupEventArgs e)
        {
                     base.OnStartup(e);
MainWindow m = new MainWindow();
Point point = m.PointToScreen(
                            new Point(320, 120));double dpiX =
               96.0 * source.CompositionTarget.TransformToDevice.M11;
           double dpiY =
               96.0 * source.CompositionTarget.TransformToDevice.M22;

           m.Left = point.X * 96.0 / dpiX; ;
           m.Top = point.Y * 96.0 / dpiX; ;*/&lt;/pre&gt;</pre>
   m.Show();
}