app: add color index label to the palette editor.

3 jobs for backport_palette_index in 28 minutes and 9 seconds (queued for 1 second)
latest
Status Job ID Name Coverage
  Babl
passed #421555
babl-git

00:03:26

 
  Gegl
passed #421556
gegl-git

00:07:14

 
  Gimp
passed #421557
build-git-autotools

00:17:28