Review for Provider for Google Calendar by Ligemer
Rated 5 out of 5 stars
Thunderbird changed some cookie settings and broke this plugin. It's less on the developer (who did a great job writing it) and more on the user to fix their settings like he suggested a few times. The other review is spot on, and my new version works after I add the cookie exception.
Anyone having problems with authentication (oauth) check your cookie settings and exceptions. Worked great for me (thanks again).
To create your own collections, you must have a Mozilla Add-ons account.