Rated 4 out of 5 stars
Thank you for this add-on! It's quite useful to customize Firefox to one's own preferences. It's easy to use and seems to do what it should be doing.
Nonetheless, an update would be nice to use it without the menu (now the add-on is accessible via menu: Tools > Key settings). I would probably put it in the Preferences window as separate section, called "Keymap" like in NetBeans -- but such a modification might not be possible due to security limitations in Firefox. An icon like other add-ons use it would also work.