pxart fill

fill FILE[:frame] KEY [--region x,y,w,h] [-o OUT]

usage: pxart fill [-h] [--region REGION] [-o O] [--dry-run] file key

  fill FILE[:frame] KEY [--region x,y,w,h] [-o OUT]   paint a rectangle (default: the frame; '.' clears)

positional arguments:
  file
  key

options:
  -h, --help       show this help message and exit
  --region REGION
  -o O
  --dry-run        print what the edit says and a diff of the file it would change; write nothing

See also, in pxart help all: EDITING (-o OUT gets the whole file, only changed lines are
  rewritten, 'no change'); FORMAT: selecting frames (FILE:SEL, an unnamed grid's name, zsh's
  "${F}:sel").

pxart help all has the whole reference, pxart help TOPIC one part of it.

This is the output of pxart help fill. The other editing commands and their shared notes are in pxart help EDITING.