This is great to see: a framework with all the pieces you need to build Firefox extensions for your own libraries.
Ongoing We are currently looking for libraries that are interested in adapting, evaluating and possibly deploying LibX. Librarians: if your library uses Millenium, Horizon, or Voyager, getting your own edition of LibX can take as little as 15 mins, and we are willing to help you set it up. We will add other OPACs as there is interest.
LibX was created by Annette Bailey and Godmar Back.
I think this is a great development.