Copy/Cut & Paste

Cool little program!

I was trying copy/paste, but it wasn't working. Does it do the current line like nano? or does text have to be selected? Didn't see any info on how to select text.

Start by running the editor and testing the reported copy, cut, paste, and text-selection behavior described in the issue. Review the existing keyboard shortcuts and selection handling, then document or correct the behavior so users can select text and use copy/paste as intended.

Written by the indexing model from the issue text.