When you close the laptop screen lid, Plasma blocks the user session. If I plug a second (HDMI in my case) screen/projector in "extend" (not screen cloning) mode then I close the laptop lid, Plasma will simply switch off the laptop screen and move all applications to second screen. No user session block will be applied. plasma-desktop-5.8.6-3.fc25.x86_64
System Settings/Power Management/Energy Saving/ There is option "Even when an external monitor is connected" Are you sure it is on?
@Dan: You changed it (a while back) so that kscreen just removes the screen unless PowerDevil suspends, right?
(In reply to Jakub Gocoł from comment #1) > System Settings/Power Management/Energy Saving/ > There is option "Even when an external monitor is connected" > Are you sure it is on? yes it is on