bug#27091: Request: Toggle scroll bar on each window separately

[Eli Zaretskii <eliz@gnu.org>]

> Date: Sat, 27 May 2017 11:57:56 +0200
> From: martin rudalics <rudalics@gmx.at>
> CC: agrambot@gmail.com, 27091@debbugs.gnu.org
> 
>  > I think this should be added to the documentation in the ELisp manual.
> 
> The doc-string of ‘set-window-buffer’ has this:
> 
>    Optional third argument KEEP-MARGINS non-nil means that WINDOW's current
>    display margins, fringe widths, and scroll bar settings are preserved;
>    the default is to reset these from the local settings for BUFFER-OR-NAME
>    or the frame defaults.
> 
> The Elisp doc of ‘set-window-buffer’ has this:
> 
>       By default, this function resets WINDOW's position, display
>       margins, fringe widths, and scroll bar settings, based on the local
>       variables in the specified buffer.  However, if the optional
>       argument KEEP-MARGINS is non-`nil', it leaves the display margins
>       and fringe widths unchanged.
> 
> I can amend the last sentence.  What else do you want to add?

The above are just fine.  The problem is on the other end: the
set-window-scroll-bars function doesn't mention that switching buffers
in the window for which that function was called will reinstate the
scroll bar.  (It also doesn't say what is the meaning of
VERTICAL-TYPE's nil value.)  And neither does the manual.