private static void HighlightFoundWindow(IntPtr hWnd)
        {
            var r = new WinApi.RECT();

            WinApi.GetClientRect(hWnd, out r);
            using (var g = Graphics.FromHwnd(hWnd))
                g.DrawRectangle(new Pen(Color.ForestGreen, 3),
                                r.Left, r.Top, r.Right - 1, r.Bottom - 1);
        }