What happens when passing `fg=...,fg=...' to region_highlight, how is this defined?

[Sebastian Gniazdowski <sgniazdowski@gmail.com>]

[-- Attachment #1: Type: text/plain, Size: 1425 bytes --]

Hello,
I'm trying to go shortcut in my plugin and in one place just append
`,fg=...' after existing `fg=...', obtaining e.g. `fg=114,fg=55',
hoping the last one will overwrite the first one.

Well, maybe it's too hard stated that I plan to do this, I just
checked if this works and obtained surprising results. Check out
attached file for the results, it is also uploaded to my shell
account: http://psprint.blinkenshell.org/fg-114,fg-55..57.png (the
file is pngcrush-ed, to limit message size).

So it's about the word "$PATH". First line is fg=114,fg=55, then
second line goes fg=114,fg=56, and third goes fg=114,fg=57 in the
region_highlight element. All 3 colors of $PATH differ in the image.
Actual color 114 is PaleGreen3 (color names from:
https://jonasjacek.github.io/colors/), actual 55..57 go from purple to
violet, all in dark brightness.

But the output, i.e. color of word "$PATH" in attached image, goes
from light green to light cyan.

So what's happening? I've tested 2 terminals, iTerm and ExtraTerm.
Also tried other combinations of colors, the results were similar, but
here I just focused on the three 55..57. I write because I sense some
possible feature heh? Some mixing of colors? Or some bug in a more
serious situation than this `double-fg=' case.

-- 
Sebastian Gniazdowski
News: https://twitter.com/ZdharmaI
IRC: https://kiwiirc.com/client/chat.freenode.net:+6697/#zplugin
Blog: http://zdharma.org

[-- Attachment #2: fg-114,fg-55..57.png --]
[-- Type: image/png, Size: 11216 bytes --]