Thanks Frumph.
Odd,though. That post is from September. This was working fine for me until 3.5. (I should have mentioned as much. )
Very frustrating to lose functionality like that, but I’ll try doing it the way you suggest. )
(If any developers are reading this, I’d like to suggest that it’s dangerous to allow iframes in previews and live post editing, but then strip then out of scheduled posts when they go live. That’s the worst possible time to make changes without the user’s knowledge! )