ScreenGrab does work in FF Ver.10! Rated 5 out of 5 stars
Worked in 3.62 , didn't work in version 9 and was disabled.
You got to keep this compatible in future versions. This is one of my all time favorites! Simple! No F keys to enable and just a right click away. Hint: Magnify +/- with Ctrl + scroll wheel adds more versatility. Perfect for your own web site screen shots! Compose tutorials fast and easy or anything if it opens in the browser. I only wish it were compatible with the windows desktop.