Rated 5 out of 5 stars

Great job! As an alternative in future you can use 4t tray minimizer - but I was able to tune it only by clicking tab panel. It doesn't recognize FF or TB window buttons as windows native ones.

Yeah, thx for reply - I just read about it after writing a comment) It's kinda sad that guys from FF team are polishing anything but the API for one of the most popular addon. "It's a matter of time" seems to be the most polite expression to describe my feelings - it has been almost a year since FF 57.

This review is for a previous version of the add-on (1.4.4). 

Hi, there is no compatibility with Firefox, because this addon still uses old APIs whose support ended with Firefox Quantum.
Nevertheless it seems not impossible to do in the future a program using WebExtensions, compatible with Firefox and Thunderbird :)
It's a matter of time...