So recently I've started using google calendar as I like the event notifications etc. I also started using Thunderbird and downloaded an extension which allowed me to open google calendar in a separate tab. I was also looking for a way to integrate google calendar into unity (so I would get notifications for events). When I gave up on this, it turned out that I had managed it somehow (see screenshot). I now get event notifications as well as a list of events below the unity calendar.
I don't know how I did this, but if someone knows how to do this, it would be helpful to know for the purposes of turning it on/off in the future. Perhaps it's Thunderbird's integration with unity? Or is my gmail account somehow connected with my unity sign-in?