Today I encountered a problem with the screen-saver, in which it couldn't be deactivated in order to return to normal work. Normally, hitting escape will deactivate the screen-saver, but this did not work. I could see the mouse pointer over top of the screen-saver, however.
I use hot-corners to activate the screen-saver, and I could still use those to re-activate the screen-saver, but then the escape key brought me back to the screen-saver "underneath", instead of the normal desktop. I could also activate mission control/spaces, and it looked normal, but choosing a desktop just brought me back to the screen-saver.
So, a summary of strategies I tried to get the screensaver "unstuck":
- hitting escape
- moving the mouse
- re-activating and de-activating the screensaver via its hot corner
- activating mission control with a hotkey and choosing a desktop
- hitting cmd-opt-escape to try the force quit dialog
How can the screensaver be deactivated without shutting down the machine? I'm running MacOS 10.13.4.