Hi
after double click of listitem in listbox a popwindow will open.i am able to get this using below code but when i clicked on another listitem.i am not able to get a popupwindow.after closing the previous one,able to get current selection.

<script type="text/javascript" language="javascript">
function display()
{
debugger;
var list=window.document .getElementById ("ListBox1");
var text=list.options[list.options.selectedIndex].text;
var text1=list.options[list.options.selectedIndex].text;
if(text==text1)

window.open("addform.aspx","mypage","scrollbar=no,height=500,width=300,resize=0,menubar=0,location=0");
}
//page_load
ListBox1.Attributes.Add("ondblclick", "javascript:display();");

I don't know what you're trying to do with the compare if(text==text1) since they will always be equal. You're comparing the same value every time. If you are trying to pass the selected value to a child window (or popup), try this:

Parent.aspx:

<form id="Form1" method="post" runat="server">
 <asp:listbox id="ListBox1" ondblclick="openWindow(this)" runat="server">
  <asp:listitem value="1">Item 1</asp:listitem>
  <asp:listitem value="2">Item 2</asp:listitem>
  <asp:listitem value="3">Item 3</asp:listitem>
  <asp:listitem value="4">Item 4</asp:listitem>
  <asp:listitem value="5">Item 5</asp:listitem>
  <asp:listitem value="6">Item 6</asp:listitem>
 </asp:listbox>
</form>

<script type="text/javascript">
<!--
function openWindow(elementRef)
{
 var selectedIndex = elementRef.selectedIndex;
 var selectedValue = elementRef.options[selectedIndex].text;

 var windowUrl = 'Child.aspx?selectedValue=' + selectedValue;
 var windowName = 'Window_' + new Date().getTime();
 var windowFeatures =
  'channelmode=no,directories=no,fullscreen=no,' +
  'location=yes,dependent=yes,menubar=no,resizable=no,scrollbars=yes,' +
  'status=no,toolbar=no,titlebar=no,' +
  'left=0,top=0,width=500px,height=300px';

 window.open(windowUrl, windowName, windowFeatures);
}
// -->
</script>

Child.aspx.cs:

private void Page_Load(object sender, System.EventArgs e)
{
 string selectedValue = (this.Request["selectedValue"] == null) ? string.Empty : this.Request["selectedValue"];
 this.Response.Write("selectedValue [" + selectedValue + "]<br>");
}

NC...

Thank you very much i got the solution