25 std::unique_ptr<Filesystem> filesystem;
26 std::unique_ptr<GraphicsResourceCache> graphics_resource_cache;
27 std::unique_ptr<Window> window;
28 std::unique_ptr<Graphics> graphics;
29 std::unique_ptr<Audio> audio;
30 std::unique_ptr<LayerStack> layer_stack;
36 bool minimized =
false;
37 std::optional<double> last_frame_time_seconds;