adding $state.controlledBy( controller[, state_name ])
function.
well, if you want to see if the current state is the "last valid state", that's not a parent of currently active state.
sample:
given states (controllers will be referred with tne same name):
a
a.a1
a.a1.a2
when current state is a.a1.a2
, $state.controlledBy( ctrl )
will return true only for a.a1.a2
's controller