Rated 4 out of 5 stars

Version 0.5 works nicely. I "inspected" an appointment, Ctl-A, Ctl-C, open a text editor, Ctl-V, save as a .ics file. Deleted the appointment, then recreated it from Thunderbird by opening the .ics file. What's not to like? Just add a "Save As..." option.

This review is for a previous version of the add-on (0.5). 

Thanks for the feedback. I've added this option in version 1.0, which is currently under review.