(almost) perfect ball collisions

[jimmynewguy]

I got bored and made this almost perfect ball physics demo, it's only almost perfect because i haven't found any problem so i know there must be
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Red - stationary
white - moves with no gravity
blue - moves with gravity (sometimes go crazy)

EDIT:
actually on the collision on any actor for x2 it should be +(width/2) not - srry