Code (C++)

        public MainForm()
		{
			InitializeComponent();

            Diagram.RegisterItemClass(typeof(ShapeNodeEx), "ShapeNodeEx", 1);
......
}

        class ShapeNodeEx : ShapeNode
        {
            public ShapeNodeEx(ShapeNode prototype) : base(prototype)
            {
            }
            public ShapeNodeEx()
            {
            }

            public string MoreText { get; set; }

            public override void DrawLocal(Drawing.IGraphics graphics, RenderOptions options)
            {
                base.DrawLocal(graphics, options);

                StringFormat drawFormat = new StringFormat();
                graphics.DrawString(MoreText, new Font("Yahei", 7), Brushes.DarkBlue , (float)(Bounds.Width * .5), (float)(Bounds.Height*.85), drawFormat);
            }

            protected override void SaveTo(System.IO.BinaryWriter writer, PersistContext ctx)
            {
                base.SaveTo(writer, ctx);
            }

            protected override void LoadFrom(System.IO.BinaryReader reader, PersistContext ctx)
            {
                base.LoadFrom(reader, ctx);
            }

        }