bug#56691: outline-minor-mode displays navigation arrow buttons as emojis

[Jim Porter]

On 8/10/2022 4:39 AM, Po Lu via Bug reports for GNU Emacs, the Swiss 
army knife of text editors wrote:
> So, has there been a conclusion here on what to do or not?
> It is really not acceptable for Emacs to display arrow buttons in a form
> that depends on the fonts installed on a user's system.  Why can't we
> default to what Custom does, which is to use an SVG (or failing that,
> PBM) image instead?

It looks like icons.el supports defining an image to use via 
'define-icon', so shouldn't this "just" be a matter of defining that 
appropriately? Then users can customize 'icon-preference' to their 
hearts' content. I tried looking into how to do that, but it wasn't 
clear to me how to use an image with 'define-icon'.

I agree that we should provide image files for these icons though, 
especially since we already use these images in Customize.