JavaScript which hooks to the OnClientActiveTabChanged=”OnTabChanged” event of the TabContainer. When the event is called the currently selected tab index is pulled and saved to the hidden form field.

<script type="text/javascript">
    function OnTabChanged(sender, args) {
        var tabControl = $get("").control;
        var currentIndex = tabControl.get_activeTabIndex();
        $get("").value = currentIndex;
    } 

.csharpcode, .csharpcode pre
{
font-size: small;
color: black;
font-family: consolas, “Courier New”, courier, monospace;
background-color: #ffffff;
/*white-space: pre;*/
}
.csharpcode pre { margin: 0em; }
.csharpcode .rem { color: #008000; }
.csharpcode .kwrd { color: #0000ff; }
.csharpcode .str { color: #006080; }
.csharpcode .op { color: #0000c0; }
.csharpcode .preproc { color: #cc6633; }
.csharpcode .asp { background-color: #ffff00; }
.csharpcode .html { color: #800000; }
.csharpcode .attr { color: #ff0000; }
.csharpcode .alt
{
background-color: #f4f4f4;
width: 100%;
margin: 0em;
}
.csharpcode .lnum { color: #606060; }

Hidden form filed added to ASCX or ASPX view.

<asp:HiddenField ID="hfSelectedIndex" runat="server" />

.csharpcode, .csharpcode pre
{
font-size: small;
color: black;
font-family: consolas, “Courier New”, courier, monospace;
background-color: #ffffff;
/*white-space: pre;*/
}
.csharpcode pre { margin: 0em; }
.csharpcode .rem { color: #008000; }
.csharpcode .kwrd { color: #0000ff; }
.csharpcode .str { color: #006080; }
.csharpcode .op { color: #0000c0; }
.csharpcode .preproc { color: #cc6633; }
.csharpcode .asp { background-color: #ffff00; }
.csharpcode .html { color: #800000; }
.csharpcode .attr { color: #ff0000; }
.csharpcode .alt
{
background-color: #f4f4f4;
width: 100%;
margin: 0em;
}
.csharpcode .lnum { color: #606060; }

Method for setting the ActiveTabIndex of the TabContainer if there is a value in the hidden form field.

        private void SetCurrentTab()

        {

            if(!string.IsNullOrEmpty(hfSelectedIndex.Value))

            {

                int value;

                if (int.TryParse(hfSelectedIndex.Value, out value))

                    tcStoreEditor.ActiveTabIndex = value;

            }

        }

Call the SetCurrentTab method in the Page_Load event to set the selected index if one exists.

        protected void Page_Load(object sender, EventArgs e)

        { 

            if (!Page.IsPostBack)

            {

                //Some Method Calls Here

            }

            SetCurrentTab();

        }