bug#4854: 23.1.50; before-string overlay and show-paren-mode

[npostavs]

Eli Zaretskii <eliz@gnu.org> writes:

>> From: npostavs@users.sourceforge.net
>> Date: Sun, 03 Jul 2016 11:36:01 -0400
>> Cc: 4854@debbugs.gnu.org
>> 
>> Well, it's possible to avoid moving overlays to minibuffer, but then
>> show-paren-mode stops working in the minibuffer, which I don't think is
>> so great.
>
> To say the least.  Please don't, I edit expressions in the minibuffer
> quite a lot, and find show-paren invaluable in general and there in
> particular.

Don't worry, I wasn't intending to.  That patch was just for
demonstration.  I suppose it might be possible to have paren overlay
per-buffer, so that the overlay doesn't disappear and reappear all the
time, but I don't think it's worth the complication.  I'm pretty sure it
would remain possible to write a command that's able to observe some
inconsistencies regardless: since show-paren-mode relies on idle-timers,
the behaviour is affected by the timing of the user's keystrokes.  It's
best to write commands that are oblivious to what show-paren-mode does
(e.g., the (cl-some ...) condition I posted in that same message).