Subject: Re: bug#53776: Modeline indicator when using define-minor-mode

From: Michael Heerdegen <[email-masked]>
Date: Mon, 07 Feb 2022 00:59:31 +0100

Stephen Berman <[email-masked]> writes:

> > #+begin_src emacs-lisp
> > (defvar ml-scroll-amnt 0)
> >
> > (setq-default
> >  mode-line-format
> >  `(:eval (substring (format-mode-line ',mode-line-format)
> >                     ml-scroll-amnt)))
> > #+end_src
> >
> > and let mouse-4 and mouse-5 over the mode-line de- and increase
> > `ml-scroll-amnt'.  That's all.
>
> Thanks, but doesn't this just truncate the mode-line-string
> continuously?  For scrolling back, it seems necessary to store the
> original mode-line-string and concatenate the previously truncated part
> of it with the current value.

No, you just have to change the value of `ml-scroll-amnt'.  Try it.
That piece of code doesn't work as you describe.

Michael.