SDL_SetRenderDrawColor(_renderer, 0, 255, 0, 255);
SDL_RenderClear(_renderer);
const SDL_Rect r = { x, y, w, h };
SDL_SetRenderDrawColor(_renderer, r, g, b, a);
SDL_RenderFillRect(_renderer, &r);
SDL_RenderPresent(_renderer);

const char *error = SDL_GetError();
if (*error != '\0') {
	fprintf(stderr, "%s\n", error);
	SDL_ClearError();
}