code: function(cmp) {
          var me = this,
              newGroup = cmp,
              oldGroup;
  
          if(Ext.isString(cmp)) {
              newGroup = Ext.getCmp(newGroup);
          }
  
          if (newGroup === me.activeGroup) {
              return true;
          }
  
          oldGroup = me.activeGroup;
          if (me.fireEvent('beforegroupchange', me, newGroup, oldGroup) !== false) {
               me.activeGroup = newGroup;
               me.fireEvent('groupchange', me, newGroup, oldGroup);
           } else {
               return false;
           }
           return true;
      }
docs: Makes the given group active
  @param {Ext.Component} cmp The root component to make active.