How do I used gravity to make the Player slide off an edge?

So on my platformer, my player is standing off the edge of a ledge. If he is more than 50% off the edge I want him to start sliding such that he will eventually fall off ... right now if even his "tippy toe" is there he stays level.

Any thoughts?

You could either make the collision polygon on the player smaller than the player so his feet dont fit in the box or I believe if you make the colision polygon an up sidedown trapazoid the bottom edges will be at an angle and he should slide off.. would be careful though as im not sure how these will affect the rest of your the game play...

You can make invisible sprite

And when player overlapping sprite

(Sub event ) Every tic ------------- set player platform x to to 100

I don't know if this will help , but might be close .