code: function (item, checked) {
          var value = [];
          this.items.each(function(item){
              if (item.checked) {
                  value.push(item.value);
              }
          });
          this.selected = value;
  
          this.fireEvent('checkchange', item, checked);
      }
docs: Handler for the 'checkchange' event from an check item in this menu
  @param {Object} item Ext.menu.CheckItem
  @param {Object} checked The checked value that was set