Wince嵌入式开发时，C#怎么绘制圆角的控件？

using System;
using System.Drawing;
using System.Windows.Forms;
using OpenNETCF.Drawing;

namespace SmartButton
{
    public partial class UserControl1 : UserControl
    {
        public UserControl1()
        {
            InitializeComponent();
        }
        /// <summary>
        /// 控件重绘
        /// </summary>
        /// <param name="e"></param>
        protected override void OnPaint(PaintEventArgs e)
        {
            base.OnPaint(e);
            e.Graphics.Clear(Color.Transparent);

            IntPtr hdc = e.Graphics.GetHdc();
            GraphicsEx gx = GraphicsEx.FromHdc(hdc);
            PenEx p=new PenEx(Color.Black);
            gx.DrawRoundRectangle(p, this.ClientRectangle, new Size(10, 10));

        }
        /// <summary>
        /// 将控件背景设置为透明（ System.Drawing.Color.Transparent;）
        /// 需要重写这个方法，但不用做任何事，防止控件闪烁
        /// </summary>
        /// <param name="e"></param>
        protected override void OnPaintBackground(PaintEventArgs e)
        {

        }
    }
}