This apparently has been going on since Beta 5 - maybe earlier - but I just realized it: all my Sarafi Windows shrink from full-height to something smaller whenever I switch to my XP VM (in full screen mode) and back again to OS X. This does not happen with Firefox (?). The shrinkage is from the bottom of the Safari window, i.e. the Safari window shrinks up from the bottom by about an inch and a half (on my MBP). Repeatable, every time I switch OSes.
