xtermjs/xterm.js

Support DECSLRM (SMGLR, SMGLP, SMGRP) - Set Left and Right Margins for better scrolling performance in multi-pane TUIs

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#4,285 opened on Dec 2, 2022

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Description

Ref. #2358

Also known as Set Left and Right Margins. This feature is used by terminal applications like tmux and (neo)vim to optimize pane scrolling. Real xterm supports it, many not-real-xterms don't, so Neovim patches out this functionality for xterm pretenders (which it tries to detect via the XTERM_VERSION environment variable).

Right now, forcing Neovim to use the smglr results in this: https://asciinema.org/a/Qcgm1znQy3nE8DnCc0jnrjXMi (versus not using them).

Contributor guide

Tech stack
typescript
Domain
cliperformance
Issue type
feature
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
3
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
1-2 days
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
stale
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
clear
Prerequisites
Understand DECSLRM specificationFamiliarity with xterm.js parserAbility to test changes in terminal emulator
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
55
Research direction
Review the DECSLRM specification at vt100.net and examine how xterm.js currently parses escape sequences. Look at the existing handling of similar margin or scrolling features in the codebase, likely in files like InputHandler.ts. The issue references #2358 for additional context. Test with terminal applications like tmux or neovim to verify correct behavior.