Render Problem in TabContainer

Hi,

I encounter a problem in using Ajax Control Toolkit 4.0 for .net 4.0

When I upgrade to ajax 4.0 from ajax 2.0, I find that it renders header label incorrectly in Ajax Tab Container. After some checking, I find it render the header twice if there is a component in header template. How can I solve the problem?

<act:TabContainer ID="tcControl" runat="server" ActiveTabIndex="0" AutoPostBack="false"><act:TabPanel ID="tpSearch" runat="server"><HeaderTemplate><asp:LinkButton ID="TabContainerHeaderSearch" runat="server" Width="150" Text="Search" OnClick="TabContainerHeader_Click" /></HeaderTemplate><ContentTemplate><asp:Panel ID="plSearch" runat="server">
                            Test</asp:Panel></ContentTemplate></act:TabPanel></act:TabContainer>

Screen Capture (Ajax 2.0 Correct Version)

Screen Capture (Ajax 4.0 Incorrect Version)