Rated 5 out of 5 stars

Very good add-on, it has just two minor issues.
The wallet is not reopened (if closed) and Firefox and Thunderbird password windows appear with the same message.

I managed to fix both problems in my forked repository:
https://github.com/maciex/mozilla-kwallet

Guillermo please merge the changes and/or contact me (Support site link for the add-on is not working).
Thanks !

This review is for a previous version of the add-on (1.14). 

Which distro are you using? in ubuntu libxul is no longer available.
Cheers