控件的属性是个类，如何给添加自定义属性(C#)

using System;
using System.Collections.Generic;
using System.Text;
using System.Data;
using System.Collections;
using System.Windows.Forms;

namespace CSFramework.Tech2011
{
   /// <summary>
   /// 扩展DataRow.通过扩展DataRow，我们的新MyDataRow拥有属性:UserFullName 和方法GetUserFullName()
   /// 注意：这里又用到Composite模式.这个模式太基础，应用无处不在.
   /// </summary>
   public class MyDataRow
   {
      private DataRow _source = null; //组合DataRow
      public DataRow Row { get { return _source; } }
      
      public MyDataRow(DataRow source)
      {
         _source = source;
      }
      
      //注意：扩展DataRow，新属性
      public string UserFullName
      {
         get
         {
            return "ID:" + _source["user_id"].ToString() + " NAME:" + _source["user_name"].ToString();
         }
      }
      
      //如果举例还不够，再加个方法
      public string GetUserFullName()
      {
         return "ID:" + _source["user_id"].ToString() + " NAME:" + _source["user_name"].ToString();
      }
   }
   
   /// <summary>
   /// 组合模式演示，将DataTable.Rows由构造器传入。
   /// 这个类组合DataTable.Rows ,用IList结构存储。
   /// </summary>
   public class MyDataRows
   {
      private IList _rows;
      
      /// <summary>
      /// 构建索引器
      /// </summary>
      public MyDataRow this[int index]
      {
         get { return (MyDataRow)_rows[index]; }
      }
      
      //将DataTable.Rows由构造器传入。
      public MyDataRows(DataRowCollection rows)
      {
         _rows = new ArrayList();
         
         //因传进参数rows为DataTable.Rows,而不是MyDataRow的Collection.需要转换
         foreach (DataRow r in rows)
         {
            MyDataRow temp = new MyDataRow(r); //构建自己的类
            _rows.Add(temp);
         }
      }
      
      //设计一个自定义的方法.
      public MyDataRow FindRowByFieldValue(string fieldName, string value)
      {
         foreach (MyDataRow row in _rows)
         {
            if (row.Row[fieldName].ToString().ToUpper() == value.ToUpper())
            return row;
         }
         return null;
      }
   }
   
   /// <summary>
   /// 自定义DataTable .也是Compoiste
   /// </summary>
   public class MyDataTable
   {
      private MyDataRows _MyRows = null;
      public MyDataRows MyRows { get { return _MyRows; } }
      
      public MyDataTable(DataTable source)
      {
         _MyRows = new MyDataRows(source.Rows);
      }
   }
   
   /// <summary>
   /// 测试用的类
   /// </summary>
   public class vjsdn_Composite
   {
      private MyDataTable CreateTestTable()
      {
         DataTable dt = new DataTable();//创建一个自己的类
         dt.Columns.Add("user_id", typeof(string));
         dt.Columns.Add("user_name", typeof(string));
         DataRow row;//增加两条测试记录
         row = dt.NewRow();
         row["user_id"] = "001";
         row["user_name"] = "csdn";
         dt.Rows.Add(row);
         
         row = dt.NewRow();
         row["user_id"] = "002";
         row["user_name"] = "vjsdn";
         dt.Rows.Add(row);
         
         return new MyDataTable(dt);
      }
      
      public void Test()
      {
         MyDataTable dt = CreateTestTable();
         
         //注意这里(MyRows属性及FindRowByFieldValue方法)。调用自定义的方法!
         MyDataRow yes = dt.MyRows.FindRowByFieldValue("user_name", "csdn");
         if (yes != null)
         MessageBox.Show(yes.Row["user_name"].ToString());
         else
         MessageBox.Show("没找到!!!");
      }
      
      /// <summary>
      /// 测试MyDataRow的方法和属性
      /// </summary>
      public void Test1()
      {
         MyDataTable dt = CreateTestTable();
         
         MessageBox.Show(dt.MyRows[0].GetUserFullName()); //读自定义方法
         MessageBox.Show(dt.MyRows[1].UserFullName); //读自定义属性
      }
   }
}