How to dynamically update a tab title

I notice that there's no setter for 'title' in a tab - but I need to update it dynamically with a number indicating a count. I tried the following code but the display does not change:

Code:

            
viewModel.bind('{numReservations}', function(val) {  var newTitle = 'Reservations (' + val + ')';
  var tabpanels = Ext.ComponentQuery.query('#regionCenter');
  if(tabpanels.length) {
    var tabpanel = tabpanels[0];
    var tab = tabpanel.child('#tabreservations');
    tab.title = newTitle;     // The value does change here, but the display does not
    tabpanel.updateLayout();  // Tried this but nothing changes
  }
});

... how do I get the change in title value to be visible?

Thanks,

Neil

How to dynamically update a tab title