OSC 18 Tektronix Cursor Color

OSC 18 ; Pt ST sets the color of the cursor in xterm’s Tektronix 4014 window, and OSC 18 ; ? ST asks what it is. OSC 118 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 moves on to color 19.

The Tektronix colors belong to xterm’s second window, which emulates a Tektronix 4014 graphics terminal and is opened from a menu or with CSI ? 38 h. They can be set and asked for whether or not that window is showing.

A default xterm starts it as the text cursor’s color (charproc.c), so in the terminal the cases run in, set up as a default xterm, it is reported as rgb:0000/0000/0000.

libghostty-vt has no such color, and ignores OSC 18 and OSC 118, so the cases that ask are known differences.

Validation

OSC18-1: Ask for it

\e]18;?\a

|____|
reply \e]18;rgb:0000/0000/0000\a

OSC18-2: Change it

\e]18;#0080ff\a
\e]18;?\a

|____|
reply \e]18;rgb:0000/8080/ffff\a