Used to be simply the best screenshot extension -- clean, reliable, etc. So much so, staff here bought a dozen+ copies, back when it was still "buy" rather than "free, but contribute". And recommended it to everyone who asked ...
Since then, and the arrival of E10S in FF, it's non-functional. Repeated communications with the developer just get "looking into it" or "working on it" . A few MONTHS later, still nothing.
Repeated empty promises over time == abandonware.