Let me reply Dave+Sam...
I want a Plain Box look (no title bar) but I want the functionality of Floating Window which is always the topmost Window within the app. (Dave: The Plain Box doesn't do this.)
The code in the question makes a Floating Window look like a Plain Box, but of course the call is a Carbon call. My question is: What is the Cocoa equivalent? Or, in Dave terms, I'd use a Plain Box, but how can you make it always the topmost window? What is an appropriate Cocoa call in that case?
BTW, this is for a very typical Splash Screen that shows when app is starting up. My scheme is that the Splash Screen shows up, has a Label that shows what is going on ("init this, init that"), then the main application screen appears UNDERNEATH the Splash Screen, and then 1-2 seconds afterward the Splash Screen fades out, completing the nice dovetail effect. Sam, typically Splash Screens are just a graphical box and don't have title bars.
(And, giving a heads up, I have about 8 other Carbon calls that I need to find a Cocoa equivalent for. There isn't a common list of these, is there? I googled, didn't find anything (yet).)