> Displaying inline images instead of characters us rather straightforward, actually; here's what a patch might look like (with your defcustom patch, it would be even simpler: only the defcustom would change).
Thanks for the example.
That's just a simplified example, though, right? Because we cannot
unconditionally use an SVG image; cannot even assume any kind of
images is always supported, in fact.
So, what do you reckon is the way forward about this issue? I'm willing to make a better attempt at my defcustom patch, but I'm not sure there's enough consensus for it to then be accepted.