How did Snape see Lupin the night of the Prank?

Mon Jan 27 01:20:03 UTC 2003

No: HPFGUIDX 50707

--- In HPforGrownups at yahoogroups.com, Maria Kirilenko wrote:

<< So, do we stick to the idea that no one saw any need to install a 
door, and Snape saw Lupin through the open hole, pacing in the room 
above? >>

I've always imagined that there was a thick-ish wooden door blocking 
the trapdoor but Werewolf!Lupin, driven mad by the scent of human, 
scratched and bit at it, and clawed enough of an opening for Snape to 
glimpse a silhouette of wolf snout, and put two and two together.