ASP.NET

<br />
public class CustomButton : Control , IPostBackEventHandler , IPostBackDataHandler<br />
    {<br />
        public event EventHandler Click;<br />
<br />
        protected override void Render(HtmlTextWriter writer)<br />
        {<br />
            writer.Write("<input type="\"Submit\"" name="\"ClickButton\"" value="\"Click" me="" mode="hold" />        }<br />
<br />
        #region IPostBackEventHandler Members<br />
<br />
        public void RaisePostBackEvent(string eventArgument)<br />
        {<br />
            OnClick(new EventArgs());<br />
        }<br />
        protected virtual void OnClick(EventArgs e)<br />
        {<br />
            if (Click != null)<br />
                Click(this, e);<br />
        }<br />
<br />
        #endregion<br />
<br />
        #region IPostBackDataHandler Members<br />
<br />
        public bool LoadPostData(string postDataKey, System.Collections.Specialized.NameValueCollection postCollection)<br />
        {<br />
            Page.RegisterRequiresRaiseEvent(this);<br />
            return true;<br />
        }<br />
<br />
        public void RaisePostDataChangedEvent()<br />
        {<br />
            <br />
        }<br />
<br />
        #endregion<br />
    }<br />
<br />

protected void Button1_Click(object sender, EventArgs e)
{
    if (this.FileUpload1.HasFile)
    {
        Response.Write("Yay!");

    }
    else
        Response.Write("Nay!");
}