Ah, that other thread wasn't about the firefox-specific way to do it, though, so while I could've disabled it globally, it's not the same - a
bit smaller stupid-badge for me, then
TheQwerty: yep, that'd work, but would still be an annoyance... and not
much easier than simply saying "don't warn about this file again" first time you launch a downloaded file. One of the reasons my google-fu was unsuccessful was probably that I knew a bit too much about the problem - instead of trying "
Open File Security Warning (Firefox)", my search query was "
firefox alternate data streams"