Could you highlight it incrementally? Like 500 lines per increment or something?
I thought about highlighting 200 (200 is just an example number) lines under the current line position but I'm afraid of scrolling down and seeing messed up highlighting.
Could you explain what you mean by incrementally? I think I know what you're talking about.
The trick for fast highlighting is just to calculate the visible lines instead of highlighting the total amount of lines.
I thought about that also, but I don't know how to get the visible lines from a textarea.
ALSO: klepto: that looks very nice!