An interesting writeup about what the author calls “modal overlays,” and I usually name “inline popups” such as the many dialogs on Facebook, or the preferences window on the web version of MobileMe.

It is uniquely powerful at quieting these nervous questions. “Where am I?” is a non-starter because you never left the original screen. And “How do I get back?” is trivial when the original screen remains visible in the background.

I’m going to start thinking about using that kind of tricks. (Which goes for Ajax, as well.)

It’s a good rule of thumb to think that if elements in the same context all have the same size, then they must be equally important. Apple’s Preferences modal applies the same principle to the scale of entire screens. The preferences screen is itself smaller than the browser window that plays host to the more important screens full of real data.