See http://en.wikipedia.org/wiki/Xpra http://en.wikipedia.org/wiki/Xpra as an existence proof. It's an implementation of exactly what you describe using X's ex

See http://en.wikipedia.org/wiki/Xpra http://en.wikipedia.org/wiki/Xpra as an existence proof. It's an implementation of exactly what you describe using X's existing compositing manager. It has some nice properties over using something like "xmove".