bug#28182: maybe implement CTRL++ to zoom text

[Drew Adams]

> I think this is a good idea, which has the usability benefit to mirror
> what happens in many common browsers, and other common text editors.
> I remember myself that I was struggling to find the binding to change
> the font size when I was an Emacs beginner.
> 
> I have implemented this suggestion in the attached patch.
> 
> However, this will be an incompatible change, since this was
> previously bound to scrolling up and down by close to a full screen.
> I therefore moved that binding to the meta modifier and wrote a NEWS
> item that explains how to get the old functionality back.
> 
> How does it look?

I'm not sure that mouse-4 and mouse-5 have that meaning
for all mice and platforms.  Some mice have separate
mouse-4 and mouse-5 buttons.

I think this is the right way to do it:

(global-set-key (vector (list 'control mouse-wheel-up-event))
                'text-scale-increase))

(global-set-key (vector (list 'control mouse-wheel-down-event))
                'text-scale-decrease))

I've been using that for years, and I use it all the time.

---

But I bind them to `zoom-in' and `zoom-out', which can
zoom either the buffer (via `text-scale-(in|de)crease)
or the frame (via `zoom-frm-(in|out)').  A prefix arg
toggles between buffer and frame zooming.

https://www.emacswiki.org/emacs/download/zoom-frm.el