Appearance
Highlight background (OSC 17)
ESC ] 17 ; spec BELOSC 17 sets or queries the terminal's selection highlight background color. The query is
ESC ] 17 ; ? BEL and the terminal responds with the color in X11 rgb:RR/GG/BB format, matching the OSC 10/11 response pattern. Setting uses ESC ] 17 ; spec BEL where spec is an X11 color name or rgb:RR/GG/BB. This allows applications to customize the selection appearance — useful for themes that need the selection highlight to contrast with custom foreground/background colors. Supported by xterm, iTerm2, foot, and other xterm-compatible terminals.How this is testedautomated
Query highlight background color with
Query highlight background color with
OSC 17 ; ? BEL, verify response matches OSC 17 ; rgb:... pattern via feedCapture.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 3 of 9 terminals (33%). Part of the Rich TUI baseline.
Supported by 3 of 14 backends (21%)
Terminal Applications
| Terminal | Version | Support | Notes |
|---|---|---|---|
| iTerm2 | 3.6.9 | ✓ yes | |
| Terminal.app | ✓ yes | ||
| Ghostty | 1.3.1 | ✗ no | No OSC 17 response |
| VS Code | ✗ no | ||
| Warp | ✗ no | ||
| Cursor | ✗ no |
Headless Backends
Parser correctness only — a ✓ means the parser accepts the sequence.
| Backend | Version | Support | Notes |
|---|---|---|---|
| Alacritty | 0.26.0 | ✗ no | OSC 17 highlight background query requires a real display — headless backends have no color palette to query |
| Kitty | 0.40.0 | ✗ no | OSC 17 highlight background query requires a real display — headless backends have no color palette to query |
| vt100.js | 0.2.1 | ✗ no | Not implemented — pure TypeScript emulator |
| vterm | 0.2.0 | ✗ no | OSC 17 highlight background query not implemented in vterm.js |
| WezTerm | 0.1.0-fork.5 | ✗ no | OSC 17 highlight background query requires a real display — headless backends have no color palette to query |
| xterm.js | 5.5.0 | ✗ no | OSC 17 highlight background query requires a real display — headless backends have no color palette to query |