size_t nlayers;
	Monitor *m, *moni, *insertmon = NULL;
	/* The mode is a tuple of (width, height, refresh rate), and each
	 * monitor supports only a specific set of modes. We just pick the
	 * monitor's preferred mode; a more sophisticated compositor would let
	 * the user configure it. */
	wlr_output_set_mode(wlr_output, wlr_output_preferred_mode(wlr_output));

	Monitor *m = wlr_output->data = calloc(1, sizeof(*m));
	m->wlr_output = wlr_output;

	/* Allocates and configures monitor state using configured rules */
	m = wlr_output->data = calloc(1, sizeof(*m));
	m->wlr_output = wlr_output;

	/* Initialize monitor state using configured rules */
	for (size_t i = 0; i < LENGTH(m->layers); ++i)
		wl_list_init(&m->layers[i]);

	/* The mode is a tuple of (width, height, refresh rate), and each
	 * monitor supports only a specific set of modes. We just pick the
	 * monitor's preferred mode; a more sophisticated compositor would let
	 * the user configure it. */
	wlr_output_set_mode(wlr_output, wlr_output_preferred_mode(wlr_output));

	nlayers = LENGTH(m->layers);
	for (size_t i = 0; i < nlayers; ++i)
		wl_list_init(&m->layers[i]);