groupFlags
bool isLocked = (ref->group()->groupFlags() & NodeGroup::GROUP_LOCKED);
group->groupFlags() | NodeGroup::GROUP_LOCKED :
group->groupFlags() & ~NodeGroup::GROUP_LOCKED;
uint32 groupFlags() const;
!(producer->group()->groupFlags() & NodeGroup::GROUP_LOCKED) &&
!(consumer->group()->groupFlags() & NodeGroup::GROUP_LOCKED))
!(producer->group()->groupFlags() & NodeGroup::GROUP_LOCKED))
!(consumer->group()->groupFlags() & NodeGroup::GROUP_LOCKED))