User61956409 posted
Hi cristinadoro,
As far as I know, if you set Enabled="false" to TabPanel, the “ajax__tab_disabled” CSS class will applied to this tab.
<div>
<ajaxToolkit:TabContainer ID="TabContainer1" runat="server" Height="150px" ActiveTabIndex="0">
<ajaxToolkit:TabPanel ID="TabPanel1" runat="server" Enabled="false">
<HeaderTemplate>
Tab1
</HeaderTemplate>
<ContentTemplate>
Content1
</ContentTemplate>
</ajaxToolkit:TabPanel>
<ajaxToolkit:TabPanel ID="TabPanel2" runat="server">
<HeaderTemplate>
Tab2
</HeaderTemplate>
<ContentTemplate>
Content2
</ContentTemplate>
</ajaxToolkit:TabPanel>
</ajaxToolkit:TabContainer>
</div>

Best Regards,
Fei Han