I upgraded to Ubuntu 20.04 recently and now gnome flashback sessions using metacity are acting funny. About 70% of the time, either on login, or on lock then unlock, it appears that the desktop background itself is on top of all windows, including the panel. I can see that everything is still running using ps. I have a dual monitor setup, and have a couple more data points that the background is covering windows:
- On a second screen, windows are visible, but when dragged to the other screen they are not visible
- The screen where windows are not visible sometimes is showing the lockscreen background rather than the regular desktop background
- This happens in a single monitor config as well, so it seems to affect only the main screen
- Sometimes windows can be brought to the foreground through tabbing through them.
- Killing the panel and restarting brings it to the foreground.
The left screen is the main screen and is using the lockscreen background image rather than the desktop image. The mouse cursor is not visible on this screen unless over an app window. The terminal was opened on the right screen then dragged over to the left. There are other windows that were opened on the left before locking the screen, but they are no longer visible.
