Rated 1 out of 5 stars

by 27in-iMac on July 20, 2017 ·

Mac Sierra 10.12.6 - Thunderbird 52.2.1 (64 bit)
Disabled then Enabled Add-ons until I found the culprit which was hiding the red, orange and green menu bar buttons

This review is for a previous version of the add-on (20.7). 

by Philippe V. (Developer) on July 24, 2017 ·

this is fixed in the current 21.1... sorry...