Hmm, just one further comment regarding this (should have tested it in Oolite before posting...):
I have just tested the modifications I was doing to one of my HUDs and unfortunately Oolite does not accept the colour format rgb(255, 255, 255) in its plist files, it only accepts (255, 255, 255) without the rgb bit. Of course it is trivial to replace all 'rgb' at once in Atom once the work is done (select a single 'rgb', Alt + F3 then del) but this kind of defeats the purpose of this package since the very best thing about it is how easy it is to both create a new rgb colour code as well as to modify
an existing one, but the latter needs the rgb() bit. Also, for languages that accept the rgb() format, one can use the pigments
package to visualize colours in the code itself, which is super handy:
Anyway, not a good tip for Ooliters in the end, but perhaps someone else might find this useful.