On Nov 29, 2005, at 11:50 AM, Allan Odgaard wrote:

If any (Cocoa) hacker feels like giving it a shot (to tamper with the NSOutlineView to give it a dark look), I welcome code contributions, but it's not an area where I'll spend resources myself (ATM).

I don't think this is what you're talking about.
But, anyone can mess around in the .nib files if they have Interface Builder installed.

check out my version of textMate here => http://subtlegradient.com/articles/2005/12/04/pimp-my-textmate