If one tries to add an extension through Firefox, it installs it in the users homedir under ~/.mozilla, which means, if you have a bunch of users, every user has to download his copy of the add-on individually, and it is pretty redundant to have it installed in every users homedir.

It would be best, if a add-on could not only be installed systemwide, but also preconfigured, so that when I add a new user to the system, he already has that add-on configured and activated right from the first start of Firefox. Can this be done somehow?

If it is of any relevance, the extension I'm interested in installing is Flashblock.

Cheers.

Edit: The OS is Gentoo.

Here's how I'd do it: configure a basic Firefox the way you want for a new user, then (as root) copy this user's .mozilla/firefox/ inside /etc/skel/, which is the template for new users, as far as I know.

Yves.