private void save_with_background_Button_Copy_Click(object sender, RoutedEventArgs e)
        {
            StrokeCollection sc = InkCanvas.Strokes;

            byte[] inkData = null;
            using (MemoryStream inkMemStream = new MemoryStream())
            {
                sc.Save(inkMemStream);
                inkData = inkMemStream.ToArray();
            }
            byte[] gifData = null;
            using (Microsoft.Ink.Ink ink = new Microsoft.Ink.Ink())
            {
                ink.Load(inkData);
                gifData = ink.Save(PersistenceFormat.Gif);
            }
            File.WriteAllBytes("c://strokes.gif", gifData);
        }