用JAVASCRIPT从弹出的窗口中获取值

设三个页面：Father.aspx    SubOpen.aspx    SubModalDialog.aspx

在Father.aspx中：

<asp:Button ID="Button1" runat="server" Text="一般窗口" OnClientClick="openwin() />

<asp:Button ID="Button2" runat="server" Text="模态窗口"  OnClientClick="openmodalwin()"/>

<asp:TextBox ID="backvalue" runat="server"></asp:TextBox>

写JAVASCRIPT函数：

<script language="javascript">

   function openwin()
   {

   var 

 childwin=window.open ("Sub.aspx","1","height=400px,width=400px,top=400px,left=400px");

   childwin.Fvalue.value="一般窗口";

   }
   
   function openmodalwin()
   {