I have a Lenovo Yoga 3 11 laptop with Ubuntu 15.04. When I plug the HDMI cable to my external monitor, the system goes into multi-monitor mode so I can use the laptop display and the external monitor and move windows across both displays.
When I unplug the HDMI cable, I would expect the display to return to single monitor mode (laptop display only). Instead, my external monitor goes blank (of course), but Ubuntu still thinks it's connected so I can still move windows off the edge of the screen. Why doesn't it automatically switch back?
It's able to detect on connection of HDMI and change modes, but not on disconnection. I know I can press the keyboard combination to cycle between modes, but this is more of a workaround.