If more colors did end up being allowed, I would imagine it would actually have an RGB type syntax.
This is sort of what it comes down to. You could
easily extend mIRC to use 99 colours 0-98 (99 is transparency), that would only cause minor issues with unsupporting clients. The problem would be: which 99 colours would be standardized as the default? A palette based solution needs standardized colour choice, otherwise doing something like <ctrl+k> + 10,40 could easily overlay 2 very similar shades of blue in one client, making the text unreadable, while making it completely readable (yellow on black for instance) in another. This is why if there were ever any new standardization for colours, it would be RGB, not palette/index based-- but an RGB system would NOT be backwards compatible with mIRC's current colour parsing mechanisms, so that would be problematic too.
