Add truecolor support for themes with custom colors

[Roopesh2]

Description:
When using other color schemes, except basic-color, the terminal shows a blue background

How to reproduce it:

• Build from source as in https://github.com/d99kris/nchat?tab=readme-ov-file#build-from-source
• nchat --setup
• copy dracula color scheme: (but goes same for all except basic-color')
  • cp $(dirname $(which nchat))/../share/nchat/themes/dracula/* ~/.nchat/
• run nchat with and without TERM=xterm-256color (though this seems to have no effect)

Screenshots:
basic-color works well

but dracula doesn't work as expected

Environment:

• Version: 4.41
• OS / distro: Debian 12
• Terminal : Konsole

[d99kris]

Hi @Roopesh2 - thanks for reporting an issue. I will try to look into this to see whether it's something nchat can easily support, or whether I'll need to leave it out-of-scope. For time being the workarounds would be to use themes that use standard palette (i.e. not RGB 0x112233 values), or use another terminal. Based on some quick googling I believe this other issue describes the problem with using custom palette in ncurses apps in Konsole.

[d99kris]

I have done some research on this, and it seems it's not trivial to support this. I will leave it out of scope for now and convert this issue to a feature request. Maybe some other developer with experience in this area like to contribute.