event/notification for focus?

FROM : Luc Vandal
DATE : Wed Apr 06 20:57:13 2005

Hi!

is there any event/notification for when a control gains focus? I did
search in the documentation and they mention that you can get notified
when your control has focus but I can't seem to find any code to do it
(I know how to register for a notification, but I don't know which
class has that notification nor the notification name)!

Also, is there some quick reference people use to quickly find stuff
like that? I dunno if it's my PC dev background but I always have a
hard time to find out about pretty much anything in the documentation
for Cocoa. :)

Thanks!

Luc