Comment 11 for bug 1626935

Is this a modesetting driver issue? I believe I've seen this happen when hotplugging an external monitor. It only happens for me with the modeset driver, though, not the intel driver. The modesetting driver is excellent for some things (eg it doesn't tear on the external monitor like the intel driver does), but it does struggle a bit when changing resolutions and screen layouts (eg every time I log in, it completely unnecessarily changes my laptop screen resolution from 1920x1080 to 640x480 and then back again to 1920x1080).