Dagger has it together! Rated 4 out of 5 stars
This is a review for both the browser(I run Palemoon- not Failfox) and Thunderbird versions because it works in both and perhaps it should be amended to add that it is restartless.
Dagger should be complimented because he makes a number of add-ons that at first glance make what appear to be minor changes. However, they tend to correct a whole host of downgrades that Mozilla keeps cranking out with the whole rabid-release fiasco.