Ashley: r76 here.
Nevertheless even if I thought the behavior in AnD4D was an optical illusion (the sprite is moved/shrinked at the same time => gives the impression it does not move), check with this capx.
Apparently the shrinking "blocks" the red sprite movement (in that case, straight falling, black sprite hasn't any behavior).
I've modified the values to make it obvious and I would have expected the red sprite to keep on falling through the black sprite, shrinking, not getting "blocked" on it.
Or I am missing something here.