OSC 117 Reset Highlight Background Color
Put the highlight background color back as it started.
OSC 117 ST
OSC 117 ST puts the color of the background of selected text, OSC 17, back as the terminal started it, undoing any change made with OSC 17 ; Pt ST. xterm resets it to the value it started with (ResetColorsRequest).
It takes no parameter. xterm ignores an OSC 117 that carries anything after the number, OSC 117 ; 1 ST say, as a malformed sequence (do_osc); an empty one, OSC 117 ; ST, is the same as none.
libghostty-vt has no such color, and ignores OSC 17 and OSC 117, so the case that asks is a known difference.
Validation
OSC117-1: After a change
\e]17;red\a
\e]117\a
\e]17;?\a
|____|
reply \e]17;rgb:0000/0000/0000\a