Exclude rain drops below the beaker

raindrops.py

# Find the shortest beaker so we know which drops to check for collisions
# against
beakerHeights = []
shortest = 0

for beaker in level.beakers: beakerHeights.append(beaker.rect.y)
beakerHeights.sort()

if (beakerHeights): shortest = beakerHeights[0]

# Get the current drops to test for collisions
drops=pygame.sprite.Group()
for cloud in level.clouds:
  for drop in cloud.drops:
    # Only check for collisions with drops that are above or = to the top
    # of the shortest beaker
    if (drop.rect.y <= shortest):
      drops.add(drop)

for beaker in pygame.sprite.groupcollide(level.beakers, drops, False, True).keys():
  beaker.takeDrop()