That's right, in *my* Firefox - it was never a problem in most other people's Firefoxes. I'd been having problems with it for many years, in various versions of Firefox and on several different computers. I'm thinking I might even have had this problem when I was still running Linux on my main machine. Not just Google Maps, also Live Maps and a few other mapping sites. Weird, yes, but somehow it never seemed important enough to look into - I just used IE instead and it worked in there.

Anyway, I finally hunted it down and as usual the answer is simple once you know it. There was a setting in the prefs.js file in my profile: user_pref("dom.disable_image_src_set", true); Got rid of the line, now everything works. Great, eh?

How did that setting get there? I don't know, I certainly didn't insert it myself... it seems to be related to the other dom settings, which you can find from the Options dialog, with the Advanced JavaScript settings. But there's no checkbox that seems to be related to this disable_image_src_set thing. I'm guessing it was there at one time, but they removed it, leaving people with this problem. Oh well.