private void makeFullscreenPanel(Canvas canvas)
        {
            Panel panel = new Panel()
            {
                Left = 0,
                Top = 0,
                Height = canvas.Height,
                Width = canvas.Width,
                Name = "Full-screen",   // TODO: resource
                Canvas = canvas,
            };

            FullScreen fullScreen = new FullScreen()
            {
                Canvas = canvas,
                Panel = panel,
            };

            fullScreen.init(db);

            panel.FullScreens.Add(fullScreen);
            canvas.Panels.Add(panel);
        }
        public ActionResult EditFS(FullScreen fs)
        {
            if (ModelState.IsValid)
            {
                Panel panel = db.Panels.Find(fs.PanelId);
                panel.FadeLength = fs.FadeLength;
                db.Entry(panel).State = EntityState.Modified;
                //db.Entry(fs).State = EntityState.Modified;
                db.SaveChanges();

                return this.RestoreReferrer() ?? RedirectToAction("Index");
            }

            return View(fs);
        }