Back to topic (incompatible extensions) ...
My Show Image (0.4.1) has so far been rejected by 2.0. They've been fairly good in the past at keeping up with Firefox upgrades, typically within a week or 10 days, but the last entry in their "comments" is something like a year old so I wonder if they've abandoned new development.
Show Image is handy because I can Stop a page then view the image right in its original place-holder, so I don't have to wait for the whole page. Firefox's View Image, in contrast, insists on refreshing the window to display just the image, so I have to go Back (and possibly reload) if I decide I want to follow the thumbnail-link.
Too bad there wasn't a way to make View Image open a new window (or new tab), then I wouldn't need the extension.