Thanks for the info (?) on Show Image -- I'd checked for updates a few minutes ago (via Tools/Add-ons) with no luck.
Interestingly, their site shows this new one as 2 days old -- if I try to get it, I'm getting the Install Extension window OK, but it quickly gives me a "Download error -228", whatever that means. Server overload, maybe?
I guess it's just a matter of keep trying, since obviously they're still trying to keep up to date.