Try this,
protected void AddTab(object sender, DirectEventArgs e)
{
string url = e.ExtraParams["Url"];
string id = e.ExtraParams["Id"];
foreach (var item in TabPanel1.Items)
{
if (item.ID == id)
{
TabPanel1.SetActiveTab(id);
return;
}
}
var tab = new Ext.Net.Panel
{
ID = id,
Title = url,
Closable = true
};
tab.AutoLoad.Url = url;
tab.AutoLoad.ShowMask = true;
tab.AutoLoad.Mode = LoadMode.IFrame;
tab.AutoLoad.MaskMsg = string.Format("Loading {0}...", url);
tab.AddTo(TabPanel1);
TabPanel1.SetActiveTab(id);
}
<script type="text/javascript">
var click = function (id) {
var tab = TabPanel1.getComponent(id);
if (tab == undefined)
return true;
TabPanel1.setActiveTab.defer(50, TabPanel1, [tab]);
return false;
}
</script>
<form runat="server">
<ext:ResourceManager runat="server" />
<ext:Window
runat="server"
Title="Adding tab"
Width="700"
Height="500"
Icon="Link"
Layout="border">
<Items>
<ext:MenuPanel ID="MenuPanel1" runat="server" Width="200" Region="West">
<Menu runat="server">
<Items>
<ext:MenuItem runat="server" Text="Ext.Net">
<DirectEvents>
<Click OnEvent="AddTab" Before="return click(extraParams.Id)" >
<ExtraParams>
<ext:Parameter Name="Id" Value="idClt" Mode="Value" />
<ext:Parameter Name="Url" Value="http://www.ext.net" Mode="Value" />
</ExtraParams>
</Click>
</DirectEvents>
</ext:MenuItem>
<ext:MenuSeparator />
<ext:MenuItem runat="server" Text="Google">
<DirectEvents>
<Click OnEvent="AddTab" Before="return click(extraParams.Id)" >
<ExtraParams>
<ext:Parameter Name="Id" Value="idGgl" Mode="Value" />
<ext:Parameter Name="Url" Value="http://www.google.com" Mode="Value" />
</ExtraParams>
</Click>
</DirectEvents>
</ext:MenuItem>
<ext:MenuSeparator />
<ext:MenuItem runat="server" Text="Sencha">
<DirectEvents>
<Click OnEvent="AddTab" Before="return click(extraParams.Id)" >
<ExtraParams>
<ext:Parameter Name="Id" Value="idExt" Mode="Value" />
<ext:Parameter Name="Url" Value="http://www.sencha.com" Mode="Value" />
</ExtraParams>
</Click>
</DirectEvents>
</ext:MenuItem>
</Items>
</Menu>
</ext:MenuPanel>
<ext:TabPanel ID="TabPanel1" runat="server" Region="Center" />
</Items>
</ext:Window>
</form>