I'd suggest to use Add listener.
Here is the full example.
Example
<%@ Page Language="C#" %>
<%@ Register Assembly="Ext.Net" Namespace="Ext.Net" 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>Ext.Net Example</title>
<script type="text/javascript">
var addTab = function (tabPanel, id, url) {
var tab = tabPanel.getComponent(id);
if (!tab) {
tab = tabPanel.add({
id : id,
title : url,
closable : true,
autoLoad : {
showMask : true,
url : url,
mode : "iframe",
maskMsg : "Loading " + url + "..."
}
});
tab.on("activate", function () {
var item = MenuPanel1.menu.items.get(id + "_item");
if (item) {
MenuPanel1.setSelection(item);
}
}, this);
}
tabPanel.setActiveTab(tab);
}
</script>
</head>
<body>
<form runat="server">
<ext:ResourceManager runat="server" />
<ext:Window
runat="server"
Width="700"
Height="500"
Icon="Link"
Title="Adding tab">
<Items>
<ext:BorderLayout runat="server">
<West>
<ext:MenuPanel ID="MenuPanel1" runat="server" Width="200">
<Menu runat="server">
<Items>
<ext:MenuItem ID="idClt_item" runat="server" Text="Ext.Net">
<Listeners>
<Click Handler="addTab(#{TabPanel1}, 'idClt', 'http://www.ext.net');" />
</Listeners>
</ext:MenuItem>
<ext:MenuSeparator />
<ext:MenuItem ID="idGgl_item" runat="server" Text="Google">
<Listeners>
<Click Handler="addTab(#{TabPanel1}, 'idGgl', 'http://www.google.com');" />
</Listeners>
</ext:MenuItem>
<ext:MenuSeparator />
<ext:MenuItem ID="idExt_item" runat="server" Text="ExtJS">
<Listeners>
<Click Handler="addTab(#{TabPanel1}, 'idExt', 'http://www.extjs.com');" />
</Listeners>
</ext:MenuItem>
</Items>
</Menu>
</ext:MenuPanel>
</West>
<Center>
<ext:TabPanel ID="TabPanel1" runat="server">
<TopBar>
<ext:Toolbar runat="server">
<Items>
<ext:Button runat="server" Text="Button" StandOut="true" />
</Items>
<Listeners>
<AfterRender Handler="this.hide();" />
</Listeners>
</ext:Toolbar>
</TopBar>
<Plugins>
<ext:TabCloseMenu />
</Plugins>
<Listeners>
<AfterRender Handler="this.on('add', function () {
this.getTopToolbar().show();
});" />
<TabClose Handler="if (this.items.getCount() === 1) {
this.getTopToolbar().hide();
}" />
</Listeners>
</ext:TabPanel>
</Center>
</ext:BorderLayout>
</Items>
</ext:Window>
</form>
</body>
</html>
