Rated 4 out of 5 stars

per Alex Chapman el nov. 12, 2014 · enllaç permanent

This is a great extension, but unfortunately broken since Firefox version 33.

For the information of troubled users : Following some community discussions, a patched version is available here : https://github.com/ath0mas/firefox-gmail-manager-ng/blob/develop/dist/gmail_manager_ng-0.6.5.3-fixFF32.xpi
Use at your own risk.