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)
