What's the TextEditor rules on what's safe to load?

[Bruce Steers <bsteers4@xxxxxxxxx>]

Got a guy on the mailing list that likes to complain about TextEditor not
supporting some utf-8 chars.

I simply explained some time ago when he had a similar issue ...  It's a
"text" editor

but he's on one again.
Saying utf-8 BOM causes an error.
https://forum.gambas.one/viewtopic.php?t=2077

I don't know what to tell him.
Could someone explain exactly what TextEditor is built to handle and what
not to use, or complain about if it fails?

Cheers
BruceS