IntPtr hwnd = CommonCode.FindWindow("Qt5QWindowIcon", null); // получаем хендл окна Nox
// клик мышкой по полю +
CommonCode.SendMessage(hwnd, CommonCode.WM_MOUSEMOVE, IntPtr.Zero, CommonCode.MakeLParam(110,250));
CommonCode.SendMessage(hwnd, CommonCode.WM_LBUTTONDOWN, (IntPtr)CommonCode.MK_LBUTTON, CommonCode.MakeLParam(110, 250));
CommonCode.SendMessage(hwnd, CommonCode.WM_LBUTTONUP, IntPtr.Zero, CommonCode.MakeLParam(110, 250));
Thread.Sleep(2000);
CommonCode.SendMessage(hwnd, CommonCode.WM_KEYDOWN, (IntPtr)CommonCode.VK_BACK, (IntPtr)(CommonCode.MapVirtualKey(CommonCode.VK_BACK, 0)<<16|0));
Thread.Sleep(500);