Dunstblick (behind the scenes)

container.css

/* Resource ID = 1 */
TabLayout
{
  margins: 0;
  DockLayout
  {
    tab-title: "Menu";
    Button
    {
      dock-site: bottom;
      Label { text: "Exit"; }
    }
    Label
    {
      dock-site: top;
      text: "Available Applications";
      font-family: serif;
    }
    StackLayout
    {
        /* This is where the magic happens! */
        child-source: bind(1);
        child-template: resource(2);
    }
  }
}

list-item.css

/* Resource ID = 2 */
Panel
{
  DockLayout
  {
    Button {
      on-click: callback(2);
      dock-site: right;
      widget-name: bind(5);
      Label { text: "Open"; }
    }
    Button {
      on-click: callback(3);
      dock-site: right;
      widget-name: bind(5);
      Label { text: "Close"; }
    }
    Label {
      dock-site: right;
      text: bind(4);  /* port */
      margins: 0,4,4,4;
    }
    Label {
      dock-site: right;
      text: ":";
      margins: 0,4,0,4;
    }
    Label {
      dock-site: right;
      text: bind(3); /* ip */
      margins: 4,4,0,4;
    }
    Label {
      horizontal-alignment: left;
      text: bind(2);
    }
  }
}

update-list.cpp

// Update objects in local session
{
    std::vector<DiscoveredClient> clients;
    {
        std::lock_guard<std::mutex> lock{discovered_clients_lock};
        clients = discovered_clients;
    }

    ObjectList list;
    list.reserve(clients.size());

    for (size_t i = 0; i < clients.size(); i++) {
        auto const id = local_session_id(i);

        Object obj{id};

        obj.add(local_app_name /* = 2 */, UIValue(clients[i].name));
        obj.add(local_app_port /* = 4 */, UIValue(clients[i].tcp_port));
        obj.add(local_app_ip   /* = 3 */, UIValue(xnet::to_string(clients[i].udp_ep, false)));
        obj.add(local_app_id   /* = 5 */, UIValue(WidgetName(i + 1)));

        list.emplace_back(obj);

        sess.addOrUpdateObject(std::move(obj));
    }

    sess.clear(local_root_obj, local_discovery_list /* = 1 */);
    sess.insertRange(local_root_obj, local_discovery_list /* = 1 */, 0, list.size(), list.data());
}