public partial class BaseMDIForm<T> : Form
        where T:Form, new()
    {
        private static T m_Form;
        public static T Form
        {
            get
            {
                if (m_Form == null)
                    m_Form = new T();
                return m_Form;
            }
        }

        public BaseMDIForm()
        {
            InitializeComponent();
        }
    }

    public partial class StructBaseForm : BufStructBaseForm
    {
        public StructBaseForm()
        {
            InitializeComponent();
        }
    }
    public partial class BufStructBaseForm : BaseMDIForm<BufStructBaseForm> { }

public partial class BufStructBaseForm : BaseMDIForm<StructBaseForm> { }