If I close the lid (suspend) my DELL Inspiron 1545 (Ubuntu 18.04) and immediately open the lid again, the part of the screen bellow the mouse pointer flashes and is all the same colour. The area affected changes as I move the mouse.
After a reboot, the desktop icons are under the favourites. A complete power-off (i.e. remove battery) fixes things.
Probably the best answer will be don't do it! But I am puzzled.