I've found that using the unfinished themes results in UI glitches with the Layout/Event Sheet areas. I did like the look of the Office 2007 themes, but those glitches just got annoying, so I've switched back.
Basically, every time I alternated between Layout and Event Sheet, or did any other changed that cause the area to rerender, the scrollbars would flash in a fixed position about 50% the size of the sub-window. Going back to the regular theme fixed it.