protected override void OnStartDemo(SampleViewport viewport)
        {
            SetupImageList();
            for (int i = 1; i < 5; ++i)
            {
                var textbox = new LayoutFarm.CustomWidgets.SimpleBox(30, 30);
                textbox.SetLocation(i * 40, i * 40);
                viewport.AddContent(textbox);
            }
            //--------------------
            //image box
            //load bitmap with gdi+           
            ImageBinder imgBinder = new ClientImageBinder(null);
            imgBinder.SetImage(LoadBitmap("../../Demo/favorites32.png"));
            var imgBox = new CustomWidgets.ImageBox(imgBinder.Image.Width, imgBinder.Image.Height);
            imgBox.ImageBinder = imgBinder;
            viewport.AddContent(imgBox);
            //--------------------
            //checked box
            int boxHeight = 20;
            int boxY = 50;
            //multiple select
            for (int i = 0; i < 4; ++i)
            {
                var statedBox = new LayoutFarm.CustomWidgets.CheckBox(20, boxHeight);
                statedBox.SetLocation(10, boxY);
                boxY += boxHeight + 5;
                viewport.AddContent(statedBox);
            }
            //-------------------------------------------------------------------------
            //single select 
            boxY += 50;
            for (int i = 0; i < 4; ++i)
            {
                var statedBox = new LayoutFarm.CustomWidgets.CheckBox(20, boxHeight);
                statedBox.SetLocation(10, boxY);
                boxY += boxHeight + 5;
                viewport.AddContent(statedBox);
                statedBox.WhenChecked += (s, e) =>
                {
                    var selectedBox = (LayoutFarm.CustomWidgets.CheckBox)s;
                    if (selectedBox != currentSingleCheckedBox)
                    {
                        if (currentSingleCheckedBox != null)
                        {
                            currentSingleCheckedBox.Checked = false;
                        }
                        currentSingleCheckedBox = selectedBox;
                    }
                };
            }
            //-------------------------------------------------------------------
            //test canvas
            var canvasBox = new MyDrawingCanvas(300, 300);
            canvasBox.SetLocation(400, 150);
            viewport.AddContent(canvasBox);
            //-------------------------------------------------------------------

        }