Hi,

Tab labels do not support templates, however, you may set their Text which "contains" templates. For example, you may insert a button by something like

<Tabs>
  <igtab:Tab Text="New Tab <input type='button' value='but' onclick='myClick()' />"></igtab:Tab>
  ...
</Tabs>

function myClick()
{
  var tb = document.getElementById('TextBox1');
  if(tb)
    tb += 'x'; //tb.value = 'postback by tab';
  __doPostBack('TextBox1');
}

So, now on server you at least will get postback. If you have somewhere on page TextBox1 and you process its TextChange event, then that handler also should be hit.

Note: if you do similar, then there is no support in case of misbehavior or any side efffects.