RE: `y-or-n-p' does not wait for input - assumes `n'

[Drew Adams]

    To clarify, in my situation, with use-dialog-box set to nil,
    the response to:
    "Please answer y or n.  foo: (y or n)" is treated completely correctly.

    The problem is that _before that_ the mouse click (on "Foo Bar")
    apparently got treated as an (invalid) answer to the first
    "foo: (y or n)"
    question, causing the question to be repeated in its more emphatic form.

I think I'm getting the opposite behavior (!) from you with use-dialog-box =
nil.

I get "foo: (y or n)", normally, when I click Foo Bar. If I answer y or n
then, I get the correct response (Yes or No echoed in echo area).

However, if I type a character other than y or n, then I (correctly) get
"Please answer y or n.  foo: (y or n)", but if I answer y or n to that
prompt, I do _not_ get anything echoed - the "Please ..." remains in the
minibuffer.

 Creating customization buffer...done
 To install your edits, invoke [State] and choose the Set operation
 foo: (y or n)  [2 times]
 Please answer y or n.  foo: (y or n)

If I understand you correctly, you had an opposite behavior: you never saw
the first "foo: (y or n)"; you saw only the second, more emphatic version,
"Please answer y or n.  foo: (y or n)". But you see the first "foo: (y or
n)" in *Messages*. Is that correct? (This is getting a bit crazy.)

If, as you say, the pb exists in 21.3, then I should see your problem (not
my 2 pbs), but I don't. I wonder if these differences are related to
platforms. Are you on a different platform?

 - Drew