Hi Larry,
This functionality is included in the Property Hooks RFC, which will be going to a vote just as soon as Ilija finishes polishing up the test suite for it. (I think he wants to get it into a "commit as soon as the vote passes" state before we call the vote, even though that's not process-required.)
Oops, I haven't fully figured out that RFC yet and didn't realize my suggestion was included. Thanks for pointing that out!
Regards.
Saki