add message when failed to load thumbs from cloud

engine/node.h

@@ -173,6 +173,16 @@ public:
                 return static_cast<T*>(found);
         return nullptr;
     }
+    template<class T> T* add_child()
+    {
+        auto* n = new T;
+        n->init();
+        n->create();
+        n->loaded();
+        add_child(n);
+        return n;
+    }
+
     virtual kEventResult on_event(Event* e);
     virtual kEventResult handle_event(Event* e);
     virtual void handle_resize(glm::vec2 old_size, glm::vec2 new_size);;
@@ -180,6 +190,9 @@ public:
     virtual void init();
     virtual void loaded();
     const Node* init_template(const char* id);
+    void async_start();
+    void async_update();
+    void async_end();
     void add_child(Node* n);
     void add_child(Node* n, int index);
     void add_child(std::shared_ptr<Node> n);