Mutter rewinds window position on focus loss

[Marius Gedminas]

I've a dual-screen configuration. The primary screen in my laptop's internal 1920x1080. There's also an external 2560x1080 monitor plugged via a USB-C/Thunderbolt dock that is positioned above the primary screen, with their centers aligned.

After upgrading to Ubuntu 25.10 I have an issue where monitors jump to the external screen when I resume my laptop and plug in the USB C cable (this is bug 2127743). I tend to use Super+Shift+Down to move the windows to my primary screen where they're supposed to be.

Sometimes (e.g. right now) Firefox refuses to stay on the lower screen. As soon as it loses focus (eg. when I press Alt-Tab or Super+3 to focus my gnome-terminal) the window jumps to position (0, 0) of the external screen, but the size remains fixed (1920 x 1080 - height of the top bar that is only shown on the internal screen), with no decorations/borders/shadows, showing the desktop and other windows on the right and bottom.

It doesn't matter how many times I use Super+Shift+Down to move it to the primary screen, every focus loss makes it jump back.

I've seen similar reversal of position with a vertically maximized gnome-terminal: I can hold Alt and drag it left/right, but as soon as it loses focus it snaps back to the same horizontal position. (And since I use sloppy focus, it loses focus as soon as I move my mouse beyond the edges of the window.) I'm not sure it's the same bug, but the symptoms (window position reverting to an earlier value on focus loss) seems very similar.

In case it matters, my custom key gsettings include

    org.gnome.desktop.wm.preferences focus-mode 'sloppy'
    org.gnome.desktop.wm.preferences mouse-button-modifier '<Alt>'
    org.gnome.desktop.wm.keybindings move-to-monitor-down ['<Super><Shift>Down']
    org.gnome.desktop.wm.keybindings maximize-vertically ['<Shift><Super>v']

and I don't remember which of these keybindings are default and which ones I've changed.

ProblemType: Bug
DistroRelease: Ubuntu 25.10
Package: mutter 49.0-2ubuntu5.2
ProcVersionSignature: Ubuntu 6.17.0-7.7-generic 6.17.2
Uname: Linux 6.17.0-7-generic x86_64
ApportVersion: 2.33.1-0ubuntu3
Architecture: amd64
CasperMD5CheckResult: unknown
CurrentDesktop: ubuntu:GNOME
Date: Tue Dec 2 11:22:56 2025
EcryptfsInUse: Yes
InstallationDate: Installed on 2019-06-12 (2365 days ago)
InstallationMedia: Ubuntu 19.04 "Disco Dingo" - Release amd64 (20190416)
SourcePackage: mutter
UpgradeStatus: Upgraded to questing on 2025-10-29 (34 days ago)

[Marius Gedminas (mgedmin)]

There's a workaround: after Super+Shift+Down I need to unmaximize the window (Super+Down) and then maximize it back (Super+Up) and then Firefox stays where I put it after losing focus.