ok , i have tried this idea long time ago when i tried to make my 3rd game but i found some problem that its hard to do it perfectly so i made a way i think that is the best >>>
the way is : you will have 2 object and lets call them : black1, black2
ok lets say these are the events :
when player collision with win ---> then play the winning animation then fade in ( black1 ) with waiting = 2sec , then the 2nd event will be :
at the start of layout play fade out of (black2) without any waiting... so in this case you will have object for fading in and another for fading out and i made this in my latest game ( gathering the sheep ) you can check it out if you like it