New
#1
interesting, not available for extensions though, keeping mozback up then.
Read more at:The latest Firefox beta contains a feature that has been on the Mozilla support team’s to-do list for, well, “forever.” The “Reset Firefox” option is intended to help users avoid troubleshooting headaches and will be particularly handy when nothing else seems to work. What’s more, you can reset the browser without sacrificing your personal data with this one-click option.
Maximum PC | Firefox 13 Will Have Reset Button
it'd nice to not restart after (un)installing extensions (Add-ons) like chrome