Clear an icon stuck on your screen on OSX El Capitan
If you have an icon that remained on the screen over a window and if that icon will not dissappear when you move the window there’s a way to get rid of it by killing the dock. Run from OSX’s Terminal:
sudo killall Dock
Note: Maybe this bug appears on Yosemmite too, I don’t know. And maybe there’s other ways to accomplish this task but well, that’s what I did to get rid of an OSX icon stuck on my screen.