Rated 3 out of 5 stars

>>yes, right click context menu is a good idea. I will add that and also keyboard activation.

If ++ doesn't work due to the other addon - why give 2 stars only to us, if it is them?
>>The button is inserted by the new TB addon system, not by us. I will send them a bug report.

I can't believe this site doesn't allow me to reply to a reply! Strange!
Anyways, first thank you for replying promptly. Well, we all, meaning my coworkers, use mail header addons which seem to be very popular. Once you add to either context menu and/or the mail toolbar, I promise to change it to 5 stars and also make a small donation :). Kindly post here when you are done. Thank you very much.

This review is for a previous version of the add-on (2.0).  This user has a previous review of this add-on.

you can use this for issues/feature requests: https://github.com/opto/New-Thread-To-All/issues

New version 2.1 is uploaded and in the review queue.