public override string GetDesignTimeHtml(DesignerRegionCollection regions)
{
var asyncFileUpload = (AsyncFileUpload)Component;
var sb = new StringBuilder(1024);
var sr = new StringWriter(sb, CultureInfo.InvariantCulture);
var writer = new HtmlTextWriter(sr);
asyncFileUpload.CreateChilds();
asyncFileUpload.RenderControl(writer);
return sb.ToString();
}