Installable from: https://addons.mozilla.org/en-US/firefox/addon/gmail-manager-community/

This Firefox extension is a fork of Gmail Manager NG by Erik Nedwidek, itself forked from Gmail Manager by Todd Long. Development of those extensions appears to have stopped in February 2012 and March 2011.

Gmail Manager-community is available under the same licenses and is intended to be a community developed extension.

Inside "Privacy" > "History" settings from Firefox Options page:

• you should have "Always use private browsing mode" unchecked and "Accept cookies from sites" checked

Since Firefox 45, if you use Privacy Badger add-on, you may be unable to log in to your accounts:

• in the Privacy Badger settings, allow cookies for accounts.google.com.

To build XPI package, you need few tools available from your PATH:

• sed
• zip
• make (optional)

Run ./make.sh, or make (if make is installed).

New XPI is created in dist directory.

Packaging process writes logs to xpipackage.out file.

(Tested in Unix and MinGW environments)

Firefox Add-on Debugger is only available for restartless and SDK-based add-ons. So, to debug Gmail Manager-community, please use Browser Toolbox and its Debugger tool.