public partial class WebForm1 : System.Web.UI.Page
    {
        protected void Page_Load(object sender, EventArgs e)
        {
        }        protected void Button1_Click(object sender, EventArgs e)
        {
            ThreadPool.QueueUserWorkItem(new WaitCallback(ThreadProc), 30);
            System.Threading.Thread.Sleep(500);
        }        private void ThreadProc(object waitTime)
        {
            System.Web.HttpContext.Current.Response.Flush();
            //Response.Flush();
            ScriptManager.RegisterStartupScript(this, this.GetType(), "js", "alert('aa');", true);
        }
     }
在把ThreadPool.QueueUserWorkItem(new WaitCallback(ThreadProc), 30);System.Threading.Thread.Sleep(500);置于Page_Load中时可弹出对话框;置于Button1_Click时就不能弹出对话框,请教什么原因?如何解决?