# Highlight Foreground Color (OSC 19)

> Set and query the color of selected text.

- **Sequence:** `OSC 19 ; Pt ST`
- **ECMA-48:** [§8.3.89 OSC – Operating System Command, p. 51](https://archive.org/details/ecma-48-5th-edition-june-1991/page/n64/mode/1up)
- **xterm:** [Operating System Commands](https://invisible-island.net/xterm/ctlseqs/ctlseqs.html)

`OSC 19 ; Pt ST` sets the color of selected text, and `OSC 19 ; ? ST` asks what
it is. [OSC 119](https://control-codes.page/osc/reset-highlight-foreground/index.html.md) puts it back as it started. It is one
of xterm's dynamic colors, and works as [OSC 10](https://control-codes.page/osc/foreground/index.html.md) explains:
`Pt` is any color X11 can parse, and a further `;` in the same sequence is ignored, since
there is no color after it.

xterm uses the two highlight colors for a selection only in its
*highlight color mode*, `highlightColorMode`. That mode is off unless both
colors have been set to something other than the text's own colors
([`charproc.c`](https://github.com/ThomasDickey/xterm-snapshots/blob/xterm-411a/charproc.c#L11531-L11546)), so by default a selection is
shown in reverse video and these colors are not used, though they are still
kept and reported.

A default xterm starts it as the `highlightTextColor` resource, which is the background
([`charproc.c`](https://github.com/ThomasDickey/xterm-snapshots/blob/xterm-411a/charproc.c#L619)), so in the terminal the cases run in, set up
as a default xterm, it is reported as `rgb:ffff/ffff/ffff`.

libghostty-vt has no such color, and ignores `OSC 19` and `OSC 119`,
so the cases that ask are known differences.

## Validation

### OSC19-1: Ask for it

*A known difference: libghostty-vt does not pass this case.*

Input, one step per line:

```text
\e]19;?\a
```

Expected screen:

```text
|____|
reply \e]19;rgb:ffff/ffff/ffff\a
```

### OSC19-2: Change it

*A known difference: libghostty-vt does not pass this case.*

Input, one step per line:

```text
\e]19;#0080ff\a
\e]19;?\a
```

Expected screen:

```text
|____|
reply \e]19;rgb:0000/8080/ffff\a
```

---

This is the Markdown version of <https://control-codes.page/osc/highlight-foreground/>. On that page every validation case runs live in libghostty-vt, the terminal emulation core of Ghostty, compiled to WebAssembly.

The validation cases are written in the notation described in <https://control-codes.page/notation/index.html.md>.