Nitpickin': Flash before/after login screen

File under really picky-but-every-detail-counts: Using the default Fedora login/theme/background, right before the login screen show, you see a blank screen with a blue background - then the login screen comes up with the same background, but there is a quick blank/white flash before the login screen. You get the same thing after you submit the login form. Is this just something unique to a particular video card / driver set, or is it something common in all installs? Any ideas why it happens and if there's anything we can do to eliminate it? Thanks, Steven Garrity