code: function() {
          var me = this,
              // Ensure the calculated result references a Component
              result = me.getComponent(me.activeTab);
  
          // Sanitize the result in case the active tab is no longer there.
          if (result && me.items.indexOf(result) != -1) {
              me.activeTab = result;
          } else {
              me.activeTab = null;
          }
  
          return me.activeTab;
      }
docs: Returns the item that is currently active inside this TabPanel.
  @return {Ext.Component} The currently active item.