Missing icons in Firefox's menus...

At some point recently, the various icons in Firefox's various menus disappeared for me.  Oh, bookmarks, etc. still had their favicons, to be sure, but just about every other menu was sadly devoid of the icons I find so useful in quickly finding what I'm looking for.  Disaster.

A bit of googling turned up a possible cause: there's a gconf key that specifies whether menu entries should have icons or not, and these days it defaults to off it seems.  Hoorah! A easy fix...  that didn't make any difference.

Maybe it's because I use KDE and not GNOME (my other boxes with GNOME haven't exhibited this issue at all...), but I've never really known Firefox to do anything other than assume that you must be using GNOME so I'm skeptical that KDE is to blame.  Then again, KDE 4 is so delightfully GNOME like these days (Options? Nope.  Retarded UI? Hell yes!) so who knows, maybe it did persuade Firefox to take my icons away with no redress because to allow me to choose whether they were would imply that the UI isn't perfect. (Seriously: GNOME folks think like that, and KDE is starting to feel that way.  NOT what I got into Linux for at all.)  Ah, but I digress...

Anyway, persuading Firefox that it should be showing those menu icons turns out to be as simple as adding a gentle, but firm, hint to userChrome.css:

.menu-iconic-left {
    visibility: visible !important;
}

Tada! My icons are back and I'm happy again.