Thimbles & Care

This is something that’s been bothering me for a while. I’ve tried googling a solution, but none of the keywords I’ve thought to try have led anywhere close. So I’m going to describe the problem here in the off chance that someone who knows the answer sees it and tells me the solution.

I use the macOS “Terminal” command a lot. I almost always have at least two windows open, and often have more. In the preferences I’ve set their width (for almost all my profiles) to 80 characters, as Herman Hollerith intended.

My MacBook Pro has a 2880×1800 Retina display. If I understand how these things work, the “Retina” part means macOS scales things at a 2-to-1 ratio, so that it acts like a super-sharp 1440×900 display. In my office I have an external Dell 2009W display that I connect to the MacBook Pro whenever I’m at work. Its resolution is 1680×1050. (If I’m wrong about how the Retina display works, I at least know for sure that a window that fills the laptop monitor does not fill the external display.) I have the displays arranged side-by-side (not mirrored) so I can use all the screen real estate possible. I also use Mission Control, with “Displays have separate Spaces” selected in the System Preferences. Terminal is assigned to a Desktop that appears on the external monitor when it’s connected.

Very annoyingly, usually when I connect to the external monitor, the width of my Terminal windows are increased by one or two (or occasionally more) characters. When I disconnect the monitor, correspondingly, the width is decreased. It’s not consistent, though; sometimes the widths don’t change, and sometimes they change by seven or more characters. The vertical size doesn’t change (unless I’ve increased it while on the external monitor so it won’t fit on the laptop display.) I really want these windows to always be 80 characters wide, regardless of which monitor they appear on. Does anyone know of a way to fix this?