This bug happens to me also. I had this problem in my laptop during a few months. But it disappeared after a while. Now it suddenly appeared on my desktop. 16.04 LTS. I dont have other users in my computers as others mentioned. It happened after a few weeks of a fresh Ubuntu installation. Annoying but not serious. It happens after returning from screen lock or restart. Disappears after doing "ESC".
This bug happens to me also. I had this problem in my laptop during a few months. But it disappeared after a while. Now it suddenly appeared on my desktop. 16.04 LTS. I dont have other users in my computers as others mentioned. It happened after a few weeks of a fresh Ubuntu installation. Annoying but not serious. It happens after returning from screen lock or restart. Disappears after doing "ESC".