Complex sentence: The UI design was changed in OS X 10.10, where for the first time the color pinwheel actually rotates, instead of the shaded, translucent layer on top of the color pinwheel, in previous versions.
Split into simpler sentences: The UI design was changed in OS X 10.10. Also for the first time ever the color pinwheel actually rotates, instead of a shaded, translucent layer on top of the color pinwheel in previous versions.