bug#13473: 24.3.50; Display Tables doc bug

[Eli Zaretskii <eliz@gnu.org>]

> From: Stephen Berman <stephen.berman@gmx.net>
> Date: Wed, 14 Feb 2018 14:33:18 +0100
> Cc: 13473@debbugs.gnu.org
> 
> On Tue, 13 Feb 2018 20:18:41 -0500 Noam Postavsky <npostavs@users.sourceforge.net> wrote:
> 
> > Stephen Berman <stephen.berman@gmx.net> writes:
> >
> >>   The glyph used to draw the border between side-by-side windows (the
> >>   default is @samp{|}).  @xref{Splitting Windows}.  This takes effect only
> >>   when there are no scroll bars; if scroll bars are supported and in use,
> >> ! a scroll bar separates the two windows.  On graphical terminals, Emacs
> >> ! uses a thin line to indicate the border, so the display table has no
> >> ! effect.
> >>   @end table
> >
> > If it's only effective on a tty display, then is the scroll bar
> > reference irrelevant?  AFAIK, there are never scroll bars on a tty
> > display anyway.
> 
> I think that's right, so the above is misleading (with or without the
> change).

Careful here: the same could be said about the truncation and
continuation glyphs (and in fact, the manual actually did say that),
but it's incorrect, because those glyphs _are_ used on GUI frames when
the user disables the fringes.

So any such "irrelevancy" must be qualified by "currently" etc.,
because no one prevents us from implementing a feature whereby they
will be used.

I will soon install the following:

  @item 5
  The glyph used to draw the border between side-by-side windows (the
  default is @samp{|}).  @xref{Splitting Windows}.  This currently has
  effect only on text terminals; on graphical terminals, if vertical
  scroll bars are supported and in use, a scroll bar separates the two
  windows, and if there are no vertical scroll bars and no dividers
  (@pxref{Windows Dividers}), Emacs uses a thin line to indicate the
  border.