Here is the thread were this example started:
Notice that the transition(s) occur in the same scene - then there is an “instant” jump to the target scene. i.e. when we go from Scene 1 to Scene 2 the “transition” effect actually occurs in Scene 1. Going from Scene 2 to Scene 1 - ditto - the transition effect occurs completely in Scene 2 and then there is the instant jump to Scene 1. This is the type of pattern You will find useful in constructing your own custom effects.