[grey-area]

Have you looked at setLevel on NSWindow?

[dialog setLevel:NSStatusWindowLevel];

It's probably not a viable solution long-term because users will expect more Mac OS X-like behaviour and non-modal dialogs, but it would help you do what you want I think.

[andlabs]

Actually OS X is the only system that guarantees application-modal dialog boxes stay always on top; it's the other platforms that I would need to worry about.

[grey-area]

ah ok, sorry I misunderstood.