bug#25946: 26.0.50; display-buffer ignores ignores reusable-frames in display-buffer-alist

[Drew Adams <drew.adams@oracle.com>]

>  > I'll try once I know how to create special/dedicated frames.
> 
> Impossible since the "fix" for Bug#15133.  Apparently no one
> used this in the past four years.

Huh? I use special/dedicated frames all day long, everyday, as
you well know.

But I use `special-display-regexps', `special-display-buffer-names'
(including function value), `special-display-alist', etc.
Thank goodness they still work, without problem.  Without them,
I'd likely have to stop using Emacs.

If there were a clear, just-as-simple, just-as-succinct,
alternative way to accomplish the same thing, and if I were
forced to use it instead of what (still) works for all Emacs
versions (`special-display-*'), then I'd use it.

It wouldn't be convenient, because I use multiple Emacs
releases everyday, but if it were just as simple and I had no
choice then I would likely use it (in addition to using
`special-display-*' for older releases).

But AFAIK there is NO clear and just-as-simple, alternative
way to get the `special-display-*' behavior.  That's too bad.

What should be done, IMHO, instead of deprecating such
simple, useful, and straightforward user knobs, is to
continue to support (and even promote) them, even if they
might now be reimplemented using more complex mechanisms.

We should not lose these useful constructs.  They work fine
still.  They should continue to just work, as always.
Adding additional bells and whistles to Emacs should not
remove this convenient behavior and its simple user-level
constructs.