Comment # 13 on bug 939153 from Bruno Friedmann

@Wolfgang is there anything we can help to hack (about the build process)

I don't know if it support the multilanguage in the manifest and jar
Actually we have 

locale calendar en-US jar:chrome.jar!/calendar-en-US/locale/en-US/calendar/
locale lightning en-US jar:chrome.jar!/lightning-en-US/locale/en-US/lightning/

Seems easy (but certainly the trap) to add

locale calendar fr jar:chrome.jar!/calendar-fr/locale/fr/calendar/
locale lightning fr jar:chrome.jar!/lightning-fr/locale/fr/lightning/

and so on

Ideally this part of locales should goes to the language pack of thunderbird,
so if a user activate the language he want, then all TB is correctly localized.

I was hit by this a few day ago, when a user ask me why the calendar was always
in english instead of french or german.