def add_global_overlay(o): GLOBAL_OVERLAYS.append(o)
def remove_global_overlay(o): if o in GLOBAL_OVERLAYS: GLOBAL_OVERLAYS.remove(o)
def set_global_overlays(olist): for _ in range(len(GLOBAL_OVERLAYS)): GLOBAL_OVERLAYS.remove(GLOBAL_OVERLAYS[0]) GLOBAL_OVERLAYS.extend(olist)