Get the Previously Selected Tab

<form id="form1" runat="server">
   <asp:ScriptManager ID="ScriptManager1" runat="server">
   </asp:ScriptManager>
   <asp:HiddenField ID="previousTabHidden" runat="Server" />
   <script type="text/javascript">
   function OnSelecting(sender, args)
   {
       $get("<%= previousTabHidden.ClientID%>").value = sender.get_selectedTab().get_text();
   }
   </script>
   <telerik:RadTabStrip RenderMode="Lightweight" ID="RadTabStrip1" runat="server" Skin="Outlook" SelectedIndex="3" AutoPostBack="true" OnTabClick="RadTabStrip1_TabClick" OnClientTabSelecting="OnSelecting">
       <Tabs>
           <telerik:RadTab Text="Advanced">
           </telerik:RadTab>
           <telerik:RadTab Text="Automatic Updates">
           </telerik:RadTab>
           <telerik:RadTab Text="Remote">
           </telerik:RadTab>
           <telerik:RadTab Text="General">
           </telerik:RadTab>
           <telerik:RadTab Text="Computer Name">
           </telerik:RadTab>
           <telerik:RadTab Text="Hardware">
           </telerik:RadTab>
       </Tabs>
   </telerik:RadTabStrip>
</form>     

RadTab lastClickedTab = null;
protected void Page_Load(object sender, EventArgs e)
{
   if (Page.IsPostBack)
   {
       if (Request.Form["**EVENTTARGET"] == RadTabStrip1.UniqueID)
       {
           //locate the selected tab by using the value of the hidden field
           //The code below will be executed only if the postback is fired by the tabstrip
           lastClickedTab = RadTabStrip1.FindTabByText(previousTabHidden.Value);
       }
   }
}
protected void RadTabStrip1_TabClick(object sender, Telerik.Web.UI.RadTabStripEventArgs e)
{
   Response.Write("You clicked " + e.Tab.Text);
   Response.Write("</br> Previous clicked tab was " + lastClickedTab.Text);
}   

Private lastClickedTab As RadTab = Nothing
Protected Sub Page_Load(ByVal sender As Object, ByVal e As EventArgs)
    If Page.IsPostBack Then
        If Request.Form("**EVENTTARGET") = RadTabStrip1.UniqueID Then
            'locate the selected tab by using the value of the hidden field
            'The code below will be executed only if the postback is fired by the tabstrip
            lastClickedTab = RadTabStrip1.FindTabByText(previousTabHidden.Value)
        End If
    End If
End Sub
Protected Sub RadTabStrip1_TabClick(ByVal sender As Object, ByVal e As Telerik.Web.UI.RadTabStripEventArgs)
    Response.Write("You clicked " + e.Tab.Text)
    Response.Write("</br> Previous clicked tab was " + lastClickedTab.Text)
End Sub