After closing the laptop lid, and then awaking it up after some time, the Gnome desktop would show strange behavior. Namely, the screen would blink when the mouse would touch to the top bar, and the system menu would show a strange "pause button", on top of the usual row of the 3 buttons (settings, lock, shut-down).
The only way to fix this, it to put the system back to sleep, and awaking it up again - and the symptoms would disappear.
Any idea what's going on?
Thinkpad W550s Linux 4.15.0-43-generic x86_64 Ubuntu 18.04.1 LTS VGA compatible controller: Intel Corporation HD Graphics 5500 (rev 09) 3D controller: NVIDIA Corporation GM108GLM [Quadro K620M / Quadro M500M]