On the Richview newsgroups, Sergey again posted one solution for overwrite mode. I had tried that code many months ago, and it didn’t change the caret to block mode as I would have hoped, so I had written my own which didn’t quite work perfectly. Thought I’d try his again. The overwrite mode worked perfectly, but the caret change was necessary in my mind. Posted a message back to the newsgroup. Hopefully Sergey will have an easy solution.
There’s a new PAF Documentation Guidelines booklet available for $10 US, that looks like it will have useful information for me when I implement editing of sources in version 2. I have the 1995 edition, but it is quite out of date and only describes the sources in the old PAF format. I ordered a copy of the new booklet online.