PanelBar for ASP.NET AJAX Version Q3 2008 released 11/25/2008 (release history)

ASP.NET 2.0 introduces the ability to perform a postback to a different ASPX page using a cross-page postback. This can be achieved by setting the PostBackUrl property of the RadPanelBar object to the page that will handle the postback. On the second page, you can access the controls of the page, from which you have been redirected, by accessing the second page's Page.PreviousPage property.

    
    <telerik:RadPanelBar runat="server" ID="RadPanelBar1" PostBackUrl="CrossPageCS.aspx" ... />