public class ListBoxEx : System.Web.UI.WebControls.ListBox, IPostBackEventHandler
    {
        public event System.EventHandler Click;
    
        protected virtual void OnClick(EventArgs e)
        {
            if (Click != null)
            {
                Click(this, e);
            }
        }
        #region IPostBackEventHandler Members

        public void RaisePostBackEvent(string eventArgument)
        {
            OnClick(new EventArgs());
        }

        #endregion

        protected override void OnPreRender(EventArgs e)
        {
            Attributes.Add("onClick", Page.GetPostBackEventReference(this));
            base.OnPreRender (e);

        }

    }