std::sort lambda function

        auto f = [](const c_appevent &a,const c_appevent &b)->bool
        {
            if(a.m_priority < b.m_priority) return true;
            if(a.m_priority == b.m_priority) return a.idx<b.idx;
            return false;
        };

        std::sort(evts.begin(),evts.end(),f);