Feature request: properly support zero-length 'characters'

[pepa65]

I've asked about this before, but I thought it would be good to have this on Github.
When editing files with characters that get modified by zero-length characters (like in my case, Thai), those zero-length additions get represented by a ? in ne.

Most common editors have this fixed now (nano, vi) so it seems the external infrastructure is in place. Would you be willing to look into this again?

[vigna]

Maybe not for this release, but, yes. A sample file with intended result/actual result would be useful!

[pepa65]

The famous one would be https://www.cl.cam.ac.uk/~mgk25/ucs/examples/UTF-8-demo.txt
When looking at the Thai text, instead of displaying question marks, it should display the relevant tone/vowel/other marks above or under the preceding consonant.