Used to be a great add-on Assegnate 2 su 5 stelle
Nice made, fast and light weight.
Works perfectly fine for me.
Just a little small bug.
After adding the Proxy selector List button to the toolbar for the first time, the selected proxy does not show up on the button. The list appears to be correct and the selected proxy is checked also, but clicking on it does not brings its text on the button itself. After a Firefox restart, things go well again.
EDIT : The above problem still exists, but their is a major issue now. I cannot change the proxies, or add any new proxy under the Manage proxy window. The new added proxies or the edited ones remain for the current session but any change is lost after I close the Firefox. I think this is due to the fact that this add-on is using Mozilla site to store the proxy list. Currently I cannot change the proxy list from what it was in Firefox 9.