nice concept Assegnate 4 su 5 stelle
I like this concept. It's a lot of fun, has a good-looking UI that does some cool and non-obvious things.
The only thing I would change is to NOT put this add-on's options into a new pane on the Firefox options window. What if every add-on did this? What about users who are using larger font sizes -- such as those with visual difficulties -- meaning space in the (unresizable) Options window is an issue? I think the authors should just do what every other add-on does and put their options UI in its own options window.