Johnathon Suker <email@example.com> commented that my technique of copying new System Folder files over the old ones and then moving them all back again could lead to trouble if some old and unnecessary System Update file or something similar was included by this process. I should have mentioned that I always go through the resulting folders and manually scan for files I know won't work with the new System. A slower method might involve opening both the old and the new folders and manually moving (from the old to the new) just non-Apple files that you know will work. [ACE]
Two Shortcuts for App Exposé
If you want to see all the windows for a particular app via App Exposé, there are two hidden shortcuts. For either, start by pressing Command-Tab to bring up the app switcher. Then, while still holding down the Command key, press either the 1 key or the up arrow. That puts you into App Expose mode, with all of an app's windows showing, and recent documents in a row across the bottom of the screen. Let up on the Command key, and then you can press Tab to cycle through all the running apps.