Good day, Recently, I was trying to remove a wi-fi network from my system preferences as the network had transitioned to WPA2 (from WEP), so I had to remove the old network as it had the same SSID as the new one. When I clicked on the - button to remove it, the cursor beachballed when it was inside the window. When outside of the window, it reverted back to a normal cursor. After 5 minutes of waiting, I forced-quit it and this is what happened. This glitch only appears in that space and not in other spaces. The only way to get rid of this glitch is to logout and login. It happens on my two 13" rMBPs and also my 15" rMBP.