Hi,
Not sure I follow, do you mean you want to trigger an action not just by mouse interaction?
if that's the case, simply create a layer of indirection.
your action should be triggered using an event like "DO THIS ACTION":
one one side, your gui interface will receive the "MOUSE DOWN" and you simply forward that by sending a event "DO THIS ACTION".
then from any other fsm you can also trigger this action by sending this event "DO THIS ACTION", either via other ways of interaction of using an automated or following a logical set of steps in your game.
bye,
Jean