The below fails when you switch to the 2nd tab and click "Update":
<form id="Form1" runat="server">
<asp:ScriptManager runat="server" />
<ExtJS:ScriptManager runat="server" Theme="Default" />
<asp:UpdatePanel runat="server">
<ContentTemplate>
<ExtJS:TabPanel ID="tabsCustomer" runat="server" ActiveTab="0" AutoHeight="True" AutoWidth="True">
<Tabs>
<ExtJS:Tab ID="tabCustomerSearch" runat="server" Title="Customer Search" AutoHeight="True" AutoWidth="True">
<Content>
<asp:UpdatePanel ID="UpdatePanel1" runat="server" UpdateMode="Conditional">
<ContentTemplate>
</ContentTemplate>
</asp:UpdatePanel>
</Content>
</ExtJS:Tab>
<ExtJS:Tab ID="tabCustomerDetail" runat="server" Title="Customer Detail" AutoHeight="True" AutoWidth="True">
<Content>
<asp:UpdatePanel ID="UpdatePanel2" runat="server" UpdateMode="Conditional">
<ContentTemplate>
<ExtJS:Button ID="btnUpdate" runat="server" Text="Update" />
</ContentTemplate>
</asp:UpdatePanel>
</Content>
</ExtJS:Tab>
</Tabs>
</ExtJS:TabPanel>
</ContentTemplate>
</asp:UpdatePanel>
</form>
Let me know when you guys want me to test it again -- I'm going to roll back to this mornings copy :)
Cheers,
Timothy