Add color option to box outlines

[Simsalabim1234]

I have a minor feature request: Would it be possible to add an option such that box boundaries can also be customly colored? Currently there is only the option to enable / disable the outline, and depending on light or dark mode in Lichtblick, the outline is either black or white. It would be very helpfull if the outline could be set to an arbitrary color.

[aneuwald-ctw]

Hey @Simsalabim1234 yes, that is a great ideia in my opinion! We will put this in our plans and do in the future.

In the meanwhile, if you think you can develop it, be free to try and open a PR, we will be glad to review and help you.
But only if you feel comfortable, otherwise we'll do it, just can't promise when 😃

Thanks for the contribution!

Cheers,
Alex