父页面单击按钮，弹出窗口，接受用户输入，关闭当前弹出窗口，返回父页面

webform1 :   label, textbox, button
                   

private void Page_Load(object sender, System.EventArgs e)
        {
            // 在此处放置用户代码以初始化页面

            if(!IsClientScriptBlockRegistered("clientScript"))
            {
                string ss="<script>";
                ss += "function OpenWin(){";
                ss += "var  str=window.showModalDialog('WebForm12.aspx',document.Form1.TextBox1.value);";
                ss += "if(str!=null) document.Form1.TextBox1.value=str;";
                ss += "}";
                ss += "</script>";
                RegisterClientScriptBlock("clientScript",ss);
                this.Button1.Attributes.Add("onclick","OpenWin()");
            }


        }

WebForm2是个frameset，包含webform3页面，它不包含任何代码
WebForm3 label, textbox, button
private void Button1_Click(object sender, System.EventArgs e)
  {
   string ss="<script>";
   ss += "window.parent.returnValue='"+this.TextBox1.Text.Trim()+"';";
   ss += "window.parent.close();";
   ss += "</script>";
   if (!Page.IsClientScriptBlockRegistered("clientScript"))
   {
    Page.RegisterClientScriptBlock("clientScript",ss);
   }
  }