For a complete documentation of new functionality refer to:
http://community.kde.org/KWin/Shadow
The current implementation includes a new Shadow class and Toplevel
holds a pointer to an instance of this class. The Shadow class reads
the data from the X11 Property. There is one extended class located
in SceneOpenGL to render the shadow.
Compositor is adjusted to include the shadow region into the painting
passes.
Implementation for XRender still missing and Shadow needs to respond
to size changes of the Toplevel to update cached shadow region and
WindowQuads.
Martin Gräßlin