I've got a Thinkpad T470 running Ubuntu 18. I use two external monitors - one over USB3.0, the other over HDMI. When I wake the computer from sleep mode, 50% of the time it wakes up with the HDMI screen disconnected. If I now go enable that screen in display settings, my 3-screen layout resets. I have to resort to unplugging both, waiting for it to figure out how to display things on just one screen again, then plug each screen in separately, HDMI first, taking a moment to let it get its sh*t together each time. It drives me crazy. I've learned to interrupt cooking dinner and pop into my office room to jiggle the mouse just so I don't have to go through this procedure again because I hate it.
Yea, the whole psychotic dance that computers do when you plug or unplug another monitor is just a terrible user experience. This happens not just in Linux, but in macOS and Windows, too. Have two monitors and plug another one in, and it blanks both of them, screen comes back on one of them, blanks again, then comes back on another one, then a second one comes on, blanks both of them, then, if you're lucky, all three will light up in some random order. Also, if you're lucky all three monitors will display correct, most recently configured resolutions. It's so bad, and seems to affect all kinds of monitors, all kinds of graphics adapters, and all OSes. And it's been this way since the very first time I had a second monitor back in 1999. Plugging in a monitor shouldn't confuse a computer so much but here we still are.
When I plug a monitor in, I expect the other ones I'm looking at to simply stay on. This doesn't seem like a huge development effort, but what do I know?
