"wait until" or "repeat until" (with a wait) for modal dialog wait?

[Dr. Hawkins]

I am writing my own modal replacement for answer for a variety of reasons

Once I have a modal stack/card set up, there isn't anything to do but wait
for it.

I could use either

repeat until the retVal of me is not empty
   wait 10 milliseconds with messages
next repeat


or I could use

wait until the retVal of me is not empty


But is the wait until going to spike the cpu?   the dictionary states that
to evaluates "continuously"--but how continuously is continuously?

And will this be system dependent?
-- 
Dr. Richard E. Hawkins, Esq.
(702) 508-8462