OSC 19 Highlight Foreground Color

OSC 19 ; Pt ST sets the color of selected text, and OSC 19 ; ? ST asks what it is. OSC 119 puts it back as it started. It is one of xterm’s dynamic colors, and works as OSC 10 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), 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), 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

\e]19;?\a

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

OSC19-2: Change it

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

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