Compiz misplaces windows when multiple monitors at different resolutions are added and removed.

[Jeremy Phelps]

My setup:

- two 1920x1080 monitors, one in portrait orientation, the other in landscape. One of them is the
  built-in laptop monitor.
- one 3840x2160 monitor.

CCSM 0.9.13.1. Ubuntu package version: 0.9.13.1+18.04.20180302-0ubuntu1.

Setting up the bug:

Plug in all 3 monitors and, using CompizConfig Settings Manager, create a 9-workspace desktop, arranged in a 3x3 grid.

Turn on Expo. Set it to "One wall per output". Move windows to all 3 monitors in all 9 workspaces.

Unplug the external monitors. For now, they'll stay in their workspaces.

Move some windows around again.

Plug the external monitors back in. The size of the wall grows due to the addition of monitors, but the windows aren't moved to stay in their workspaces, or even to stay within the monitors. They tend to move upwards and to the left in terms of workspaces, but they're probably maintaining their absolute pixel position with respect to the whole wall. Plugging in monitors redraws the workspace boundaries, but the windows don't move to stay in their workspaces.

Conceptually, a wall made with monitors of different sizes has voids that are only visible when you zoom out. If you spread your windows out evenly before plugging in the external monitors, some of them will end up in the voids.

[Jeremy Phelps (username00001)]

Actually I was wrong: The windows get scrambled every time you change the amount of available screen space by either adding or removing monitors.

[daveola (b-launchpad-net-daveola-com)]

I have this problem if I simply do:

1) On my laptop, change the resolution from the default
2) Close the lid
3) Open the lid

Everything moves. Sadness ensues.