Great add-on! Rated 5 out of 5 stars
Great job, Philipp! Thanks for all your efforts. This is definitely the most useful Thunderbird/SeaMonkey/Mozilla add-on, and it's in daily use since the times of Netscape Communicator and Lightning's predecessor, Mozilla Calendar plugin. So many thanks also to Mike Potter and Mostafa Hosseini.
Now after updating to Lightning 2.7b1 it's again working smoothly in SM 2.22.
For all the one star rating bug reporting linux users: Please have a look at https://blog.mozilla.org/calendar/.
And please don't forget, this is a project that is kept alive by volunteers. They spend their spare time to offer free (like in free beer) high qualitiy open source code to the users.