communication between different parts of application via signals

["Joe Van Dyk" <joevandyk gmail com>]

Hi,

Say a user clicks a checkbox in a menu that affects three other parts
of the application.  Would a signal be the best way to communicate
that change to the rest of the application?  How would that work?
Would I create a custom signal or slot?  How would the other parts of
the application listen to that signal?  Would I create the slot and
then pass that slot to the other parts of the application (i.e. in a
constructor)?

Sorry for the basic questions, but signals and slots and functors are
still confusing to me.

I'm also a gigantic fan of unit testing -- are signals unit testable?

Joe