code: function(tab) {
              var index = null,
                  tabs = this.get('tabs');
              for (var i = 0, len = tabs.length; i < len; ++i) {
                  if (tab == tabs[i]) {
                      index = i;
                      break;
                  }
              }
              
              return index;
          }
docs: Returns the index of given tab.
  @method getTabIndex
  @param {YAHOO.widget.Tab} tab The tab whose index will be returned.
  @return int