Rated 5 out of 5 stars

Thank you for "reviving" the MinimizeToTray add-on ;-)

The add-on works perfectly for me. It's highly useful and convenient.
I use only two add-ons with Thunderbird, and this is one of them.
I've been using it in the past under Windows and currently under Linux Mint.

A special thanks for the quick latest update to 1.3.2:
Even though not mentioned it the changelog, it also fixed a bug for me:
Clicking the tray icon to restore the application window recently stopped working , but now works again like it did before!