Rated 5 out of 5 stars
still the best addon to minimize thunderbird
i don't want to use 3rd party tools besides addons (runs in thunderbird)
i use legacy version of thunderbird PE portable edition from portable apps dot com on sourceforge (see files tab, select thunderbird PE 45.8.0)
Unfortunately I sometimes forget and let it update, which means I have to re-install the older version. However, it goes off without a hitch and can minimize again.
I DID have to enable all addons again, though.
Too bad about mozilla going in the wrong direction.