The Cat & Mouse power lets me shift some squares and have total concealment.
The trigger says: "You hit an enemy with a melee attack."
The trigger of FoB says: "You hit with an attack during your turn."
This Monk Guide says that this power can be used right after hitting (and maybe sliding) an enemy to stay next to that enemy and give oneself a better position for the FoB. So this power could be used to hit, move and then use the FoB. This sounds nice because moving before using FoB is otherwise not possible (so far I know).
My question is, why is this possible? Is it because FoB and C&M have (on a melee attack) the same trigger and it is nowhere stated which one is triggered first so the player can decide? Or is it because C&M is a free action and free actions can be used any time?