Is there an indicator that a column is scrolled?

No horizontal indicator is drawn. I suggested changes adding vertical scroll indicators in January, which could be adapted for this.

@tslocum maybe it is possible to modify List to be easier extendable to add these features in custom UI rather than patching and maintaining custom version of tview?

Please see this document for an explanation of why I forked tview and the differences between the two.

@tslocum Just curious, have you tried this with multi-rune Unicode characters or even with characters that occupy more than one cell?

Well, the proper solution took me a few hours to figure out. It"s not as easy as it may have seen because, as in many other places,

byte ≠ rune ≠ Unicode character

So I can"t merge this PR. Sooner or later someone gets problems with emojis or foreign characters.