Comment 52 for bug 1072206

simple solution is this :

set variable minimize-fast-duration and minimize-slow-duration to both to 1.
then its should gone .

but this is is simple hack . not true fix. for reproducing this bug I notice when you minimize a window "IF" focus remain unchanged between animation . then the window become dark . try this . set duration for both fast and slow to big number . try minimize/unminimize when animation not finished . then you should see a dark window . ( I suggest gnome-monitor for trying this ) .
when you set animation duration to 1 or 0 then animation is so fast user cannot unminimze during animation.
I hope this help.
and I am pretty disappoint by nvidia support.

geforce 610M , ubuntu 14.10