SeenAt Block 1.0
IGNORE YOUR ENEMIES
When the lock is on, nobody knows you read messages on chat:
Stop showing people when you read their messages!
(Block "Seen At" in Facebook chat).
Visit www.seenatblock.com and www.facebook.com/seenatblock
This add-on has been preliminarily reviewed by Mozilla. Learn more
This add-on is not compatible with your version of Firefox because of the following: