一个自定义的页面按钮

在项目中要用到可以切换状态的图片按钮（就是鼠标离开是一个样子，鼠标移上去是一个样子，鼠标离开是一个样子）
自己做了一个简单的web控件实现这样的效果：

using System;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.ComponentModel;

namespace BusinessObjects.WebControls
{
    /**//// <summary>
    /// Summary description for ImagedButton.
    /// </summary>
    [DefaultProperty("Text"), 
        ToolboxData("<{0}:ImagedButton runat=server></{0}:ImagedButton>")]
    public class ImagedButton : System.Web.UI.WebControls.ImageButton 
    {
        private string text;
        private string enterimage;
        private string clickimage;
        private string clickaction;
    
        [Bindable(true), 
            Category("Appearance"), 
            DefaultValue("")] 
        public string Text 
        {
            get
            {
                return text;
            }

            set
            {
                text = value;
            }
        }

        [Category("Appearance"), DefaultValue(""), Description("鼠标点击时执行的脚本")]
        public string onClick
        {
            get
            {
                return clickaction;
            }
            set
            {
                clickaction = value;
            }
        }

        [Category("Appearance"), DefaultValue(""), Description("鼠标进入时的图片"), EditorAttribute(typeof(System.Web.UI.Design.ImageUrlEditor), typeof(System.Drawing.Design.UITypeEditor))]
        public string EnterImage
        {
            get
            {
                return enterimage;
            }
            set
            {
                enterimage = value;
            }
        }

        [Category("Appearance"), DefaultValue(""), Description("鼠标按下时的图片"), EditorAttribute(typeof(System.Web.UI.Design.ImageUrlEditor), typeof(System.Drawing.Design.UITypeEditor))]
        public string ClickImage
        {
            get
            {
                return clickimage;
            }
            set
            {
                clickimage = value;
            }
        }
        
        /**//// <summary> 
        /// Render this control to the output parameter specified.
        /// </summary>
        /// <param name="output"> The HTML writer to write out to </param>
        protected override void Render(HtmlTextWriter output)
        {
            //output.Write(Text);
            string strClick = "";
            if(onClick != null)
            {
                strClick = "onclick='" + onClick + "'";
            }

            string strStyle = " style=\"";
            foreach(string s in Style.Keys)
            {
                strStyle += s;
                strStyle += ":";
                strStyle += Style[s].ToString();
                strStyle += ";";
            }
            strStyle += "\"";

            output.Write("<img src = '" + this.ImageUrl + "' " + strStyle + " onmouseenter='this.src=\"" + 
                    EnterImage + "\"' onmousedown='this.src=\"" + ClickImage + 
                    "\"' onmouseup='this.src=\"" + ImageUrl + "\"' onmouseleave='this.src=\"" + ImageUrl + "\"'" + strClick + ">");
        }
    }
}