The "green"/teal color is based on one of the colors on the death mask of King Tut Ankh Amon, like the rest of the skin is, on the mask. It is used elsewhere in the skin, which this screenshot doesn't really show. Like on the back/forward buttons in Explorer in Vista. Misplaced? No. Design mistake? No. Unless you think that, and that's fine, but then you don't know which color scheme it's based on. Blue color is used for the flashing button. I suppose someone would argue to reverse the two, if they think the green one is soooo out of place.
