-int layer_render(LayerPtr layer, Camera *camera, float fa);
-int layer_event(LayerPtr layer, const SDL_Event *event, const Camera *camera);
+int layer_render(LayerPtr layer, const Camera *camera, int active);
+int layer_event(LayerPtr layer,
+ const SDL_Event *event,
+ const Camera *camera,
+ UndoHistory *undo_history);
+int layer_dump_stream(LayerPtr layer, FILE *stream);