bug#3579: 23.0.94; Customize: Cannot see error messages if use standalone minibuffer

[Drew Adams]

> This was four years ago.  Are you still seeing this problem?

Yes (but see below).

What actually happens (I might not have been aware of this
when I sent the report) is that the error message flashes in the
echo area very briefly, but it is immediately replaced by the
previous echo area contents, which might be a message, such as
`Back to top level' or it might be blank space (perhaps from
a call such as (message nil)?).

IOW, I think the problem is that the error message is transient,
and far too brief.  There is no reason to restore whatever
echo-area contents were there before.

With emacs -Q the error message remains.  It seems there is
something in my setup, besides just useing a standalong
minibuffer, that causes this.  I will try to bisect the code
later to see if I can narrow it down.  You can close this
bug, please.  If I narrow it down and find an Emacs bug I'll
report it.  Thx.