Rated 2 out of 5 stars

Unfortunately this doesn't always work and there's no way to contact the developer. A better answer for this functionality is install greasemonkey. Then go to userscripts.org and search on "show passwords". There are a bunch of scripts to do it. This is mine:
http://userscripts.org/scripts/show/69599

This review is for a previous version of the add-on (1.2.5.1).