[hobbs]

Most UI code is intrinsically event-based. e.g., "on click, do this", "on resize, do that"

Erlang comes to mind as a good event-based language. Strangely, it is rarely (if ever) used for UI.

[stcredzero]

I guess this is why Rob Pike can spend 6 months writing a concurrency-friendly language like Newsqueak, then use it to write a GUI windowing system in a coupe of hours.

http://video.google.com/videoplay?docid=810232012617965344