I like it. IMO, this could be pushed to the main skin itself as an update. Is it just main.xml edits?
No, it isn't just main.xml alterations. I thought so at first, and it was driving me crazy, but the tree and list panel highlights are actually bitmapped (that's how Noire has a 3D, reflective effect on the highlights, which is part of what makes it look old).
The modifications are to:
main.xml - a few small tweaks, other than the name of the skin itself so as to not overwrite the original).
List_Selection.png - the original in the skin is just fully transparent
Tree_Selection.png - identical to List_Selection.png
It would be easy enough to tweak the highlights in the others, if anyone cares. I don't like either of the others much, though, so... Meh. Something in-between the current Dark and Grey skins would be, I think, the best all-around default. Dark is nice, but is actually a bit too dark on screen when you're trying to use it in a brightly lit room. But the current Grey is garish, particularly at night.
I don't think I'm into it enough to do that much tweaking, though. Plus I feel bad about all the work of the original author, unless they specifically gave it an open license (which I didn't see).