Review for Provider for Google Calendar by modig
Rated 4 out of 5 stars
Great extension, but now only authenticates with Google correctly if you have cookies enabled.
Thunderbird/Google/Addon changed something, so now you need to change Options / Privacy / "Accept Cookies from sites" to ticked.
("Keep cookies until I close Thunderbird" will work).
Essential addon if you need to work with Google calendars.
To create your own collections, you must have a Mozilla Add-ons account.