Re: Refresh display after changing variable

[2QdxY4RzWzUUiLuE@potatochowder.com]

On 2021-08-02 at 22:56:41 +0200,
Michael Heerdegen <michael_heerdegen@web.de> wrote:

> Eli Zaretskii <eliz@gnu.org> writes:
> 
> > > From: Ken Goldman <kgoldman@us.ibm.com>
> > > Date: Mon, 2 Aug 2021 15:36:01 -0400
> > > 
> > > >    (defun kg-toggle-whitespace-line-column ()
> > > >       "Toggle whitespace line column between 80 and 101"
> > > >       (interactive)
> > > >       (setq whitespace-line-column (if (= whitespace-line-column
> > > > 80) 101 80))
> > > >       (whitespace-mode 1))
> > > > 
> > > > 
> > > That didn't work.
> >
> > <Shrug> It does here.
> 
> For me that works correctly in master but not in the 27.1 that comes
> with Debian.

FWIW, I have the following snippet in a function I wrote to change
tab-width:

  (let ((w (get-buffer-window (current-buffer))))
    (set-window-start w (window-start w)))

and a note that I stole that snippet from scroll-bar-maybe-window-start
in scroll-bar.el.  That function doesn't exist anymore (in Emacs 27.2),
but scroll-bar-set-window-start in scroll-bar.el does end as follows:

    (set-window-start window (point))))))