Ubuntu 18.04, two monitors. When one turns off, they don't "reset" to a single monitor. I can still move my mouse on to the turned-off monitor
Solution 1:
It depends upon which one is connected to DisplayPort and which one to HDMI.
- Turning of the DP one will force the rearrangement of your windows.
- Turning of the HDMI one will not.
This is a DisplayPort "feature".