Conditional moves. Yeah, that was the phrase we were groping for. And others have come up with this request before? Well, well, well! Maybe some day Miguel will come off Mount Olympus and say something about it some way or another.
With all due respect for the ones with encyclopedic knowledge of the discourse on this forum (or photographic memories), it does seem a good sign if certain requests pop up repeatedly and afresh. The mind that comes up with ideas is seldom the same one that spends time digging deeply down the pages and pages of previous threads.