Appearance
Cursor shape (DECSCUSR)
ESC [ N SP qDECSCUSR (DEC Set Cursor Style) changes the cursor appearance. The sequence is
ESC [ N SP q where N is: 0 or 1 (blinking block), 2 (steady block), 3 (blinking underline), 4 (steady underline), 5 (blinking bar/I-beam), 6 (steady bar). Applications use this to signal editing mode — for example, vim uses a block cursor in normal mode and a bar cursor in insert mode.How this is testedautomated
Send
Send
\x1b[6 q (DECSCUSR steady bar), verify cursor style is "beam".The same probe runs against headless backends (via Termless) and real terminal apps (via a daemon launched in each terminal). This lets us distinguish parser correctness from rendering correctness.
Analysis2026-04-06
Supported by 11 of 12 terminals (92%). Not supported by: vt100.js. Part of the Modern TUI baseline. Notes: vt100.js: Not implemented — pure TypeScript emulator.
Supported by 12 of 14 backends (86%)
Terminal Applications
| Terminal | Version | Support | Notes |
|---|---|---|---|
| iTerm2 | 3.6.9 | ✓ yes | |
| Ghostty | 1.3.1 | ✓ yes | |
| VS Code | ✓ yes | ||
| Warp | ✓ yes | ||
| Cursor | ✓ yes | ||
| Terminal.app | ✓ yes |
Headless Backends
Parser correctness only — a ✓ means the parser accepts the sequence.
| Backend | Version | Support | Notes |
|---|---|---|---|
| Alacritty | 0.26.0 | ✓ yes | |
| Kitty | 0.40.0 | ✓ yes | |
| vterm | 0.2.0 | ✓ yes | |
| WezTerm | 0.1.0-fork.5 | ✓ yes | |
| xterm.js | 5.5.0 | ~ partial | Parser handles DECSCUSR but headless mode doesn't expose cursor shape |
| vt100.js | 0.2.1 | ✗ no | Not implemented — pure TypeScript emulator |