Hi idrissb,
Please see below example
<%@ Page Language="C#" %>
<%@ Register Assembly="Coolite.Ext.Web" Namespace="Coolite.Ext.Web" TagPrefix="ext" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" >
<head runat="server">
<title>Coolite Example</title>
</head>
<body>
<form id="form1" runat="server">
<ext:ScriptManager ID="ScriptManager1" runat="server">
</ext:ScriptManager>
<script type="text/javascript">
function hlClick(title, url) {
var cntrTabPanel = <%= this.CenterTabPanel.ClientID %>;
var html = String.format("<iframe width=\"100%\" id=\"Center_iframe\" height=\"100%\" src=\"{0}\" frameborder=\"0\"></iframe>", url);
var tab = new Ext.Panel({
title: title,
html: html,
closable:true
});
cntrTabPanel.add(tab);
cntrTabPanel.setActiveTab(tab);
}
</script>
<ext:ViewPort ID="ViewPort1" runat="server">
<Content>
<ext:BorderLayout ID="BorderLayout1" runat="server">
<West Collapsible="true" Split="true">
<ext:Panel ID="West" runat="server" Title="Navigation" Width="175" Icon="PageFind">
<Content>
<ext:Accordion ID="Categories" runat="server" Animate="true">
<ext:Panel runat="server" Title="Panel1" BodyStyle="padding:6px;">
<Content>
<asp:HyperLink ID="HyperLink1" NavigateUrl="hlClick('Google','http://www.google.com');" runat="server">Google</asp:HyperLink><br/><br/>
<asp:HyperLink ID="HyperLink2" NavigateUrl="hlClick('ExtJS examples','http://extjs.com/deploy/dev/examples/samples.html');" runat="server">ExtJS examples</asp:HyperLink><br/><br/>
<asp:HyperLink ID="HyperLink3" NavigateUrl="hlClick('Ext.NET','http://forums.ext.net/');" runat="server">Ext.NET forums</asp:HyperLink><br/>
</Content>
</ext:Panel>
<ext:Panel runat="server" Title="Panel2">
<Content>
<asp:HyperLink ID="HyperLink4" runat="server">HyperLink</asp:HyperLink><br/>
<asp:HyperLink ID="HyperLink5" runat="server">HyperLink</asp:HyperLink><br/>
<asp:HyperLink ID="HyperLink6" runat="server">HyperLink</asp:HyperLink><br/>
</Content>
</ext:Panel>
</ext:Accordion>
</Content>
</ext:Panel>
</West>
<Center>
<ext:TabPanel runat="server" ID="CenterTabPanel" ActiveTabIndex="-1">
<Tabs>
</Tabs>
</ext:TabPanel>
</Center>
</ext:BorderLayout>
</Content>
</ext:ViewPort>
</form>
</body>
</html>
Hope this helps