Developer reply by DW-dev
Rated 5 out of 5 stars
As I wrote in private to the author (I'm the Italian translator of this addon), CT doesn't work anymore starting form TB 60.
Hoping it will update ASAP, I continue to give 5 stars.
Topoldo
Calendar Tweaks 7.0 is compatible with Thunderbird 60.0, and will be released within a few days.
To create your own collections, you must have a Mozilla Add-ons account.