Please extend a new method to achieve this functionality.
$.extend($.fn.tabs.methods, {
isDisabled: function(jq, which){
return jq.tabs('getTab', which).panel('options').tab.hasClass('tabs-disabled');
}
})
To check if a tab panel is disabled, try this:
var disabled = $('#tt').tabs('isDisabled', tabIndex);
console.log(disabled);