ASP.NET AJAX WebForms custom error handling question

args.set_errorHandled(true);

public class CustomUserControl : UserControl
{
   public new CustomUserControl
   {
      this.Error += new EventHandler(Page_Error);
   }

   protected void Page_Error(object source, EventArgs e)
   {
      Exception exception = HttpContext.Current.Server.GetLastError();
      // Message away
   }
}

protected void Application_Error(object sender, EventArgs e)
{

    //  fired when an unhandled error occurs within the application.
    //  ..or use an HttpModule instead
}

public class UnhandledExceptionModule : IHttpModule
{
    #region IHttpModule Members
    public void Dispose()
    {
    }

    public void Init(HttpApplication app)
    {
        app.Error += new EventHandler(app_Error);
    }

    protected void app_Error(object sender, EventArgs e)
    {
        HttpApplication app = sender as HttpApplication;
                Exception ex =  app.Server.GetLastError().GetBaseException();