Overview

Many style guides require lines to stay under a fixed column width (typically 80 or 100 characters) to keep code readable. When using text-mode editors like vi, emacs, or nano, a visible margin line makes it easy to see when you’re about to go over.

Configuration

Margin width is configured per-profile in Preferences → Profile → Scrolling.

GSetting	Key	Default	Meaning
Margin column	draw-margin	80	Column to draw the margin line at; 0 disables the margin entirely
Toggle shortcut	terminal-toggle-margin	<Ctrl><Alt>m	Keyboard shortcut to toggle the margin on and off without changing the profile setting

The toggle is useful when you want the margin visible while editing but out of the way while reading long output.