Appearance
Left/Right Margins (DECLRMM, Mode 69)
DECLRMM (mode 69) enables left and right scroll margins, similar to top/bottom margins set by DECSTBM. When enabled, DECSLRM sets the left and right margins. Scrolling and editing operations are confined to the margin area.
How this is tested: Enable DECLRMM (
CSI ? 69 h), check getMode("leftRightMargin") returns true. Confirms the backend tracks left/right margin mode.Analysis2026-03-26
Supported by 7 of 8 terminals (88%). Not supported by: Cursor. Part of the Rich TUI baseline.
Supported by 9 of 13 backends (69%)
Terminal Applications
| Terminal | Version | Support | Notes |
|---|---|---|---|
| iTerm2 | 3.6.9 | ✓ yes | |
| Ghostty | 1.3.1 | ✓ yes | DECLRMM not tracked by ghostty-web WASM backend |
| VS Code | 1.112.0 | ✓ yes | |
| Warp | 0.2026.03.18.08.24.03 | ✓ yes | |
| Cursor | 2.6.21 | ✓ yes | |
| tmux | 3.6a | ✓ yes | |
| Kitty | 0.46.2 | ✓ yes | DECLRMM not exposed via Python batch bridge |
| Terminal.app | 2.15 | ✓ yes | |
| GNU Screen | 5.0.1 | ✓ yes |
Headless Backends
Parser correctness only — a ✓ means the parser accepts the sequence.
| Backend | Version | Support | Notes |
|---|---|---|---|
| Alacritty | 0.26.0 | ~ partial | DECLRMM not exposed via alacritty_terminal API |
| WezTerm | 0.1.0-fork.5 | ~ partial | DECLRMM not exposed via wezterm-term API |
| vt100 | 0.2.1 | ✗ no | DECLRMM not implemented — pure TypeScript emulator |
| vterm | 0.2.0 | ✗ no | DECLRMM not implemented |