George wrote:And would it be possible to get the colour(s) of this player?
Yes, it would be easy to return the first (and if present, the second) company color, or a random color if the industry has no owner.
George wrote:If not, could we have one more field in the industry structure - the colour of the company that it had when it have built the industry?
You don't need a second field for that - industries already have a "color" field. We'd just need a new flag in property 1A that makes sure the color of the founder company gets written to this field instead of a random value. You wouldn't even need to care about any details; just enable recoloring without specifying a recolor sprite number, and you get the correct color. You couldn't use the second company color with this, though.
You just need to decide what would be better for you - an industry that changes color when your company changes color, and reverts to a random color on bankrupt, or an industry that gets its color from your current company, but never changes it later.
Reality is that which, when you stop believing in it, doesn't go away.—Philip K. Dick