+struct widget *
+window_add_subsurface(struct window *window, void *data,
+ enum subsurface_mode default_mode)
+{
+ struct widget *widget;
+ struct surface *surface;
+ struct wl_surface *parent;
+ struct wl_subcompositor *subcompo = window->display->subcompositor;
+
+ if (!subcompo)
+ return NULL;
+
+ surface = surface_create(window);
+ widget = widget_create(window, surface, data);
+ wl_list_init(&widget->link);
+ surface->widget = widget;
+
+ parent = window->main_surface->surface;
+ surface->subsurface = wl_subcompositor_get_subsurface(subcompo,
+ surface->surface,
+ parent);
+ surface->synchronized = 1;
+
+ switch (default_mode) {
+ case SUBSURFACE_SYNCHRONIZED:
+ surface->synchronized_default = 1;
+ break;
+ case SUBSURFACE_DESYNCHRONIZED:
+ surface->synchronized_default = 0;
+ break;
+ default:
+ assert(!"bad enum subsurface_mode");
+ }
+
+ return widget;
+}