Use view->scene_tree as toplevel for view + some legwork:

desktop.c move_to_front() calls wlr_scene_node_raise_to_top
desktop.c, ssd/include.h add LAB_SSD_{OSD, MENU, LAYER_SURFACE} enums
desktop.c desktop_surface_and_view_at() -> desktop_node_and_view_at()
cursor.c reenable cursor_rebase()
cursor.c reenable button click on layer surface

include/ssd.h

@@ -26,6 +26,9 @@ enum ssd_part_type {
 	LAB_SSD_CLIENT,
 	LAB_SSD_FRAME,
 	LAB_SSD_ROOT,
+	LAB_SSD_MENU,
+	LAB_SSD_OSD,
+	LAB_SSD_LAYER_SURFACE,
 	LAB_SSD_END_MARKER
 };