bug#64398: Buffer list

[Eli Zaretskii <eliz@gnu.org>]

> From: Po Lu <luangruo@yahoo.com>
> Cc: Eli Zaretskii <eliz@gnu.org>,  64398@debbugs.gnu.org,
>   angelo.borsotti@gmail.com
> Date: Thu, 05 Oct 2023 15:21:05 +0800
> 
> Stefan Kangas <stefankangas@gmail.com> writes:
> 
> > Eli Zaretskii <eliz@gnu.org> writes:
> >
> >>> It's tempting to just bump this to some similarly conservative value
> >>> like 15 or 12 on graphical displays, and be done with it.
> >>
> >> We could do that, but then 15 is the maximum value we could use, since
> >> it makes the menu take 24 lines, which is the largest value possible
> >> with 24-line TTY frames.
> >
> > How about something like the below?
> >
> > diff --git a/lisp/menu-bar.el b/lisp/menu-bar.el
> > index 5e837485db3..14d8d664d58 100644
> > --- a/lisp/menu-bar.el
> > +++ b/lisp/menu-bar.el
> > @@ -2314,14 +2314,16 @@ menu-bar-select-yank
> >  \f
> >  ;;; Buffers Menu
> >
> > -(defcustom buffers-menu-max-size 10
> > +(defcustom buffers-menu-max-size (if (display-graphic-p) 15 10)
> >    "Maximum number of entries which may appear on the Buffers menu.
> > -If this is 10, then only the ten most-recently-selected buffers are shown.
> > -If this is nil, then all buffers are shown.
> > -A large number or nil slows down menu responsiveness."
> > -  :type '(choice integer
> > -		 (const :tag "All" nil))
> > -  :group 'menu)
> > +If this is a number, only that many most-recently-selected
> > +buffers are shown.
> > +If this is nil, all buffers are shown."
> > +  :type '(choice natnump
> > +                 (const :tag "All" nil))
> > +  :group 'menu
> > +  :version "30.1")
> >
> >  (defcustom buffers-menu-buffer-name-length 30
> >    "Maximum length of the buffer name on the Buffers menu.
> 
> This doesn't work because menu-bar.el is preloaded and additionally
> because Emacs supports creating both GUI and terminal frames in the same
> process, whereas a feature can only be loaded once, with the value of
> display-graphic-p subject to whatever frame is selected at the time it
> is loaded.  Why not set it to 15 and call it a day?

It's possible, but then we will not be able to extend this in the
future anymore, as I explained above.  But maybe we don't care.

If we do care, then we could have an additional option, or we could
make this option accept a cons cell, or something else.