Rated 5 out of 5 stars

Perfect. Should be built in to Firefox and Thunderbird! Prevents the appearance of lots of password prompts at startup, which is a real problem if you have Google Calendar sync and Google Contacts sync with multiple Google accounts.

Note if you cancel the password prompt that this add-on shows, you get exactly the behaviour you'd get if you didn't have the add-on. No drawbacks.

This review is for a previous version of the add-on (1.3.1-signed).