Henry G was correct Rated 2 out of 5 stars
Email me when the configurable feature is available.
As is, this is very counter intuitive.
A two star rating for an add-on which exactly does what is says but which behaviour you personally don't like (or consider counter intuitive) and actually ask for an improvement is not exactly the best way to motivate the developer to implement your feature request. Please read the Guidelines for rating add-ons at https://addons.mozilla.org/en-US/review_guide to see if this is really what you meant. Meanwhile I recorded your feature request. Thanks.
Edit: Version 0.7 can be configured and implements a second style for those who don't like the GMail-style.