The opacity multiplier applied to the transition.
The opacity multiplier is clamped to the [0, 1] range when set. On a transition between two states, this property fades the transition wire and leaves the arrow solid. On a self transition, this property fades the transition arrow's border, leaving the arrow head solid.
ITransition startTransition = myStateMachine.GetTransitions(startState, nextState).First(); startTransition.Opacity = 0.5f;