Feature request: reverse-video support (DECSET 5)

[AutumnMeowMeow]

Reference: https://vt100.net/docs/vt510-rm/DECSCNM.html

DECSCNM—Screen Mode: Light or Dark Screen

This control function selects a dark or light background on the screen.

Default: Dark background.
Format
CSI
9/11 	?
3/15 	5
3/5 	h
6/8 	Set: reverse video.
CSI
9/11 	?
3/15 	5
3/5 	l
6/12 	Reset: normal display.
Description

When DECSCNM is set, the screen displays dark characters on a light background.

When DECSCNM is reset, the screen displays light characters on a dark background.
Note on DECSCNM

Screen mode only effects how the data appears on the screen. DECSCNM does not change the data in page memory.

See also #1671 .

Benefits:

• This would allow full passing of the vttest "2. Test of screen features".
• The infrastructure can be used for other purposes that might enhance accessibility. Examples:
  • A visual bell indicator (flash the pane).
  • An "input is waiting" indicator (reverse the pane, and un-reverse after keyboard input).

[imsnif]

That would be very cool. Are you interested in working on this @AutumnMeowMeow ?