Rated 3 out of 5 stars

THANK YOU, Brian!! I had disabled menu bar view, so your info solved the problem.

Updated rating: Add-on works fine. Deducting two stars for lack of support and documentation, and for the frustration factor.

Rated 1 out of 5 stars

This add-on is listed with my installed add-ons, but there is no evidence of it in Thunderbird and no way to use it. There is supposed to be an option for it under Tools, but there is not.
Tried contacting the developer but have received no response.