Active window hidden behind other on second monitor

[donquixote]

*Steps to reproduce:*
I am not sure about the exact conditions for this, and the behavior is not 100% consistent.
So I am just going to summarize how this usually happens for me.

Currently this is reported as a bug in mate-terminal, because this is what I clicked on when I did the bug report with ubuntu-bug -w.

I run a triple monitor setup:
- A: Laptop (Dell XPS 13), full HD.
- B, C: Two full HD external monitors, connected via HDMI, via a USB-C Hub.
Perhaps it is enough to test this on two monitors instead of three.

Currently I have "Undecorate maximized windows" enabled in MATE Tweak, but I remember it happened without that before.
(I use that to get rid of the title bar in Brave browser. Doing this in the application itself was causing problems)

I have a full-screen application on monitor B.
Currently this is PhpStorm, previously the same happend with Brave browser.

I have another full-screen application on monitor C.
Currently this is Brave browser.

I open a non-maximized window on top, and move it to the edge so that it overlaps with multiple monitors (most importantly B and C).
Often this is a terminal, but currently it is the "MATE Tweak" config window / dialog.
 should be displayed behind the maximized window on monitor C, but in front of the maximized window on B.
I focus the non-maximized window (e.g. terminal).
Then I focus the maximized window on monitor C.

*What I expect to happen*
When I focus the non-maximized window, that window is displayed on top of all others.
When I focus the maximized window on monitor C, the non-maximized window (e.g. terminal) should be displayed behind the maximized window on monitor C, but in front of the maximized window on B.

*What happens instead, v1*
When I focus the non-maximized window, that window is displayed on top of all others -> good.
When I focus the maximized window on monitor C, the maximized window on monitor B also jumps to the front, so the non-maximized window (e.g. terminal) gets hidden behind.

*What happens instead, v2*
When I focus the non-maximized window, it appears in the front on monitor C, but it disappears behind the maximized window on monitor B, even if that window does not have focus.

*Additional info*
Overall I find the behavior with multiple monitors buggy. The system seems to get confused every time I connect or disconnect external monitors. But this is a problem for another day.

ProblemType: Bug
DistroRelease: Ubuntu 18.04
Package: mate-terminal 1.20.0-4
ProcVersionSignature: Ubuntu 4.15.0-72.81-generic 4.15.18
Uname: Linux 4.15.0-72-generic x86_64
ApportVersion: 2.20.9-0ubuntu7.9
Architecture: amd64
CurrentDesktop: MATE
Date: Thu Dec 19 13:02:55 2019
ExecutablePath: /usr/bin/mate-terminal
InstallationDate: Installed on 2019-01-12 (340 days ago)
InstallationMedia: Ubuntu-MATE 18.04.1 LTS "Bionic Beaver" - Release amd64 (20180725)
SourcePackage: mate-terminal
UpgradeStatus: No upgrade log present (probably fresh install)

[donquixote (lemon-head-bw)]

The problem seems to be fixed by using Compiz for window management.
So I assume this is caused by Marco window manager.

However, Compiz caused other problems for me in the past (monitors flickering or shutting off), which is why I switched back to Marco.

[donquixote (lemon-head-bw)]

Correction to my report.

> *What happens instead, v2*
> When I focus the non-maximized window, it appears in the front on monitor C, but it disappears behind the maximized window on monitor B, even if that window does not have focus.

Turns out this effect was caused by the window on B (PhpStorm) being in "Full screen" mode.
This changes a lot..

Still, the other effect (v1) has happend to me in the past without anything being in fullscreen mode.

[donquixote (lemon-head-bw)]

> Still, the other effect (v1) has happend to me in the past without anything being in fullscreen mode.

When this happened to me in the past, it was usually when windows of the same application (Brave browser) were opened on monitors B and C, maximized.
Then focusing one of those would also bring the other window to the foreground.