Windows disappear on disconnecting external monitor

[dwmw2]

When I undock my laptop and the external displays are disconnected, sometimes the windows which were on those displays end up on my laptop's internal display. This is useful.

Often, however, they don't. I can still see them in the panel, and I can click on them to bring them back... but nothing happens. They are somewhere off-screen and I cannot find any way to recover those windows except to kill the application and restart it.

Often when this happens, even redocking the laptop and bringing those displays back doesn't actually get the windows back — those monitors are empty when they come back, or have only a subset of the "missing" windows.

This is an HP EliteBook 850 G3 running Ubuntu 16.04.

[Launchpad Janitor (janitor)]

Status changed to 'Confirmed' because the bug affects multiple users.

[Marc Olson (msolson)]

I have seen similar behavior on a Lenovo X1 Carbon (4th Gen) running Ubuntu 16.04, both directly attached, and through the OneLink+ dock.

I've "solved" this by disabling the internal display when I have an external display attached, and only attaching a single external display.