My newest dedicated C++ KWin style engine has just been committed, "Modern System". This one really shows why it's cool to support C++ plugins as well as pixmap themes by it's color scheme handling. It uses buttons I derived out of a KDE widget theme clone of "Aqua", but is all drawn in C++ using the user's color preferences and not pixmaps. Not only is it fast, but you don't have to edit any pixmaps to change how the graphics look with different colors schemes :) The other parts of the window decoration use a small frame and resize grip (people seemed to like this in the "Laptop" style for KWin).

Here's some screenshots:

Atlas Green KDE color scheme:

Desert Red KDE color scheme:

Blue Slate KDE color scheme:

The current settings: