Cross-Page Postback

You can have your panel bar cause postbacks to a different Web page from the one that contains it. Simply set the PostBackUrl property to the page that should handle the postback.

<telerik:radpanelbar 
    id="RadPanelBar1" runat="server" 
    onitemclick="RadPanelBar1_ItemClick"
    postbackurl="CrossPage.aspx">
    <Items > 
        ... 
    </Items >
</telerik:radpanelbar>

Once in the second page, you can access the the panel bar (or any other control) on the previous page using the Page.PreviousPage property.

public partial class CrossPageCS : XhtmlPage 
{ 
    protected void Page_Load(object sender, EventArgs e)
    { 
        if (Page.PreviousPage == null) 
        { 
            Response.Redirect("Default.aspx"); 
        } 
        RadPanelBar pb = (RadPanelBar)Page.PreviousPage.FindControl("RadPanelBar1");
    } 
}

Partial Class CrossPageVB  Inherits System.Web.UI.Page
    Protected Sub Page_Load(ByVal sender As Object, ByVal e As EventArgs) Handles Me.Load
        If Page.PreviousPage Is Nothing Then
            Response.Redirect("Default.aspx")

        End If
        Dim pb As RadPanelBar
        pb = CType(Page.PreviousPage.FindControl("RadPanelBar1"), RadPanelBar)
    End Sub
End Class

Another way to perform cross-page postbacks is to set the NavigateUrl property of RadPanelItem controls in you panel bar.