White square on my retina display

[marshmokhtari]

Suddenly a white square has appeared on my retina display. It'll always be on top of the windows. No matter how many I open. Any ideas??? See pic.

Thanks,
Marsh

 

[azentropy]

I had that happen before two, some windowing bug. I quit all my apps and it went away.

 

[marshmokhtari]

Thanks

I repaired the disk via disk utility and it went away.. Thanks!