Hi,
yep, it's not implemented very much because it is very performance hungry just to have this possibly that's probably unused for most of the usage of this action.
The way to do this is quite simple with an fsm template.
Watch all Enter and Exit collisions and triggers, and keep a counter, add one on enter, substract 1 on exit and then raise a bool to true when this counter is not 0
then you can reuse this template very easily and even probably fire a global event to the local branch ( send global event to self including children), when the bool value switches states, so other fsm simply catch these global events.
Bye,
Jean