That’s the behavior I was getting the last time I worked on this app, a few months ago, but it’s somehow stopped working and I can’t get it to work again. Specifically, what used to work was

1. Click on row to select it

2. Mouse-down in text, drag horizontally

This no longer works, and I can’t get the text to select at all unless I change the NSTextField’s mode to Editable, which causes the problems I described earlier.

I haven’t done much with the table-related code since I had this working. I’m kind of suspecting some undocumented AppKit change in 10.14.4, but there are so many variables that can affect behavior that I’m not ready to file a bug report yet.

—Jens