Bug: Forge can't tile

The failing assertion is in the window stacking code of gnome-shell (mutter), which the payload does not show Forge calling directly, so first find which Forge tiling call leads to it. Reproduce on a Wayland session with gnome-shell 50.1 and check the journal for the meta_window_set_stack_position_no_sync line when a window opens. Done means new windows tile under Forge without that assertion appearing.

Issue/Bug Description/Video Capture/Screenshots

Whenever I open a window it won't tile it, instead it opens it floating.
I freshly installed forge from source using make dev.
Looking at the logs, gnome-shell throws this error: "meta_window_set_stack_position_no_sync: assertion 'window->stack_position >= 0' failed"
I tried downgrading to gnome-shell 50 and 50.1 but I had the same problems.
Thank you for your time.

Steps to reproduce

No response

Distribution and Linux version

NAME="Arch Linux"
PRETTY_NAME="Arch Linux"
ID=arch
BUILD_ID=rolling
ANSI_COLOR="38;2;23;147;209"
HOME_URL="https://archlinux.org/"
DOCUMENTATION_URL="https://wiki.archlinux.org/"
SUPPORT_URL="https://bbs.archlinux.org/"
BUG_REPORT_URL="https://gitlab.archlinux.org/groups/archlinux/-/issues"
PRIVACY_POLICY_URL="https://terms.archlinux.org/docs/privacy-policy/"
LOGO=archlinux-logo
Linux Vultech 7.0.5-arch1-1 #1 SMP PREEMPT_DYNAMIC Fri, 08 May 2026 09:29:23 +0000 x86_64 GNU/Linux

Journal Logs from the last hour

mag 14 11:38:10 Vultech gnome-shell[2865]: meta_wayland_surface_role_notify_subsurface_state_changed: assertion 'klass->notify_subsurface_state_changed' failed
mag 14 11:38:11 Vultech gnome-shell[2865]: meta_wayland_surface_role_notify_subsurface_state_changed: assertion 'klass->notify_subsurface_state_changed' failed
mag 14 11:54:38 Vultech gnome-shell[2865]: meta_wayland_surface_role_notify_subsurface_state_changed: assertion 'klass->notify_subsurface_state_changed' failed
mag 14 11:54:39 Vultech gnome-shell[2865]: meta_wayland_surface_role_notify_subsurface_state_changed: assertion 'klass->notify_subsurface_state_changed' failed
mag 14 12:12:16 Vultech gnome-shell[2865]: Owner of volume monitor org.gtk.vfs.AfcVolumeMonitor disconnected from the bus; removing drives/volumes/mounts
mag 14 12:12:16 Vultech gnome-shell[2865]: Owner of volume monitor org.gtk.vfs.GoaVolumeMonitor disconnected from the bus; removing drives/volumes/mounts
mag 14 12:12:16 Vultech gnome-shell[2865]: Owner of volume monitor org.gtk.vfs.MTPVolumeMonitor disconnected from the bus; removing drives/volumes/mounts
mag 14 12:12:16 Vultech gnome-shell[2865]: Owner of volume monitor org.gtk.vfs.GPhoto2VolumeMonitor disconnected from the bus; removing drives/volumes/mounts
mag 14 12:12:16 Vultech gnome-shell[2865]: Owner of volume monitor org.gtk.vfs.UDisks2VolumeMonitor disconnected from the bus; removing drives/volumes/mounts
mag 14 12:12:16 Vultech gnome-shell[2865]: Shutting down GNOME Shell
mag 14 12:12:17 Vultech gnome-shell[2865]: Connection to xwayland lost
mag 14 12:12:17 Vultech gnome-shell[2865]: Using public X11 display :0, (using unix:/tmp/.X11-unix/X1 for managed services)
mag 14 12:12:17 Vultech gnome-shell[29293]: Running GNOME Shell (using mutter 50.1) as a Wayland display server
mag 14 12:12:17 Vultech gnome-shell[29293]: Unknown experimental feature 'scale-monitor-framebuffer'
mag 14 12:12:17 Vultech gnome-shell[29293]: Thread 'KMS thread' will be using high priority scheduling
mag 14 12:12:17 Vultech gnome-shell[29293]: Device '/dev/dri/card1' prefers shadow buffer
mag 14 12:12:17 Vultech gnome-shell[29293]: Added device '/dev/dri/card1' (nvidia-drm) using atomic mode setting.
mag 14 12:12:17 Vultech gnome-shell[29293]: Created gbm renderer for '/dev/dri/card1'
mag 14 12:12:17 Vultech gnome-shell[29293]: Boot VGA GPU /dev/dri/card1 selected as primary
mag 14 12:12:17 Vultech gnome-shell[29293]: Obtained a high priority EGL context
mag 14 12:12:18 Vultech gnome-shell[29293]: Using public X11 display :1024, (using unix:/tmp/.X11-unix/X1025 for managed services)
mag 14 12:12:18 Vultech gnome-shell[29293]: Using Wayland display name 'wayland-0'
mag 14 12:12:18 Vultech gnome-shell[29293]: Unset XDG_SESSION_ID, getCurrentSessionProxy() called outside a user session. Asking logind directly.
mag 14 12:12:18 Vultech gnome-shell[29293]: Registering session with GDM
mag 14 12:12:18 Vultech gnome-shell[29293]: Extension [email protected] already installed in /usr/share/gnome-shell/extensions/[email protected]. /usr/share/gnome-shell/extensions/[email protected] will not be loaded
mag 14 12:12:18 Vultech gnome-shell[29293]: Extension [email protected] already installed in /usr/share/gnome-shell/extensions/[email protected]. /usr/share/gnome-shell/extensions/[email protected] will not be loaded
mag 14 12:12:18 Vultech gnome-shell[29293]: Extension [email protected] already installed in /usr/share/gnome-shell/extensions/[email protected]. /usr/share/gnome-shell/extensions/[email protected] will not be loaded
mag 14 12:12:18 Vultech gnome-shell[29293]: Extension [email protected] already installed in /usr/share/gnome-shell/extensions/[email protected]. /usr/share/gnome-shell/extensions/[email protected] will not be loaded
mag 14 12:12:18 Vultech gnome-shell[29293]: Extension [email protected] already installed in /usr/share/gnome-shell/extensions/[email protected]. /usr/share/gnome-shell/extensions/[email protected] will not be loaded
mag 14 12:12:18 Vultech gnome-shell[29293]: Extension native-window-placement@gnome-shell-extensions.gcampax.github.com already installed in /usr/share/gnome-shell/extensions/native-window-placement@gnome-shell-extensions.gcampax.github.com. /usr/share/gnome-shell/extensions/native-window-placement@gnome-shell-extensions.gcampax.github.com will not be loaded
mag 14 12:12:18 Vultech gnome-shell[29293]: Extension [email protected] already installed in /usr/share/gnome-shell/extensions/[email protected]. /usr/share/gnome-shell/extensions/[email protected] will not be loaded
mag 14 12:12:18 Vultech gnome-shell[29293]: Extension screenshot-window-sizer@gnome-shell-extensions.gcampax.github.com already installed in /usr/share/gnome-shell/extensions/screenshot-window-sizer@gnome-shell-extensions.gcampax.github.com. /usr/share/gnome-shell/extensions/screenshot-window-sizer@gnome-shell-extensions.gcampax.github.com will not be loaded
mag 14 12:12:18 Vultech gnome-shell[29293]: Extension [email protected] already installed in /usr/share/gnome-shell/extensions/[email protected]. /usr/share/gnome-shell/extensions/[email protected] will not be loaded
mag 14 12:12:18 Vultech gnome-shell[29293]: Extension [email protected] already installed in /usr/share/gnome-shell/extensions/[email protected]. /usr/share/gnome-shell/extensions/[email protected] will not be loaded
mag 14 12:12:18 Vultech gnome-shell[29293]: Extension [email protected] already installed in /usr/share/gnome-shell/extensions/[email protected]. /usr/share/gnome-shell/extensions/[email protected] will not be loaded
mag 14 12:12:18 Vultech gnome-shell[29293]: Extension [email protected] already installed in /usr/share/gnome-shell/extensions/[email protected]. /usr/share/gnome-shell/extensions/[email protected] will not be loaded
mag 14 12:12:18 Vultech gnome-shell[29293]: Extension [email protected] already installed in /usr/share/gnome-shell/extensions/[email protected]. /usr/share/gnome-shell/extensions/[email protected] will not be loaded
mag 14 12:12:18 Vultech gnome-shell[29293]: Extension [email protected] already installed in /usr/share/gnome-shell/extensions/[email protected]. /usr/share/gnome-shell/extensions/[email protected] will not be loaded
mag 14 12:12:18 Vultech gnome-shell[29293]: Unset XDG_SESSION_ID, getCurrentSessionProxy() called outside a user session. Asking logind directly.
mag 14 12:12:18 Vultech gnome-shell[29293]: Will monitor session 5
mag 14 12:12:18 Vultech gnome-shell[29293]: Error looking up permission: GDBus.Error:org.freedesktop.portal.Error.NotFound: No entry for geolocation
mag 14 12:12:18 Vultech gnome-shell[29293]: Will monitor session 5
mag 14 12:12:18 Vultech gnome-shell[29293]: Type GITypeInfo of property NM.Object::client does not match return type GITypeInfo of getter get_client. Falling back to slow path
mag 14 12:12:19 Vultech gnome-shell[29293]: Registering display with GDM
mag 14 12:12:29 Vultech gnome-shell[31015]: Running GNOME Shell (using mutter 50.1) as a Wayland display server
mag 14 12:12:29 Vultech gnome-shell[31015]: Thread 'KMS thread' will be using high priority scheduling
mag 14 12:12:29 Vultech gnome-shell[31015]: Device '/dev/dri/card1' prefers shadow buffer
mag 14 12:12:29 Vultech gnome-shell[31015]: Added device '/dev/dri/card1' (nvidia-drm) using atomic mode setting.
mag 14 12:12:29 Vultech gnome-shell[31015]: Created gbm renderer for '/dev/dri/card1'
mag 14 12:12:29 Vultech gnome-shell[31015]: Boot VGA GPU /dev/dri/card1 selected as primary
mag 14 12:12:29 Vultech gnome-shell[31015]: Obtained a high priority EGL context
mag 14 12:12:30 Vultech gnome-shell[31015]: Using public X11 display :0, (using unix:/tmp/.X11-unix/X1 for managed services)
mag 14 12:12:30 Vultech gnome-shell[31015]: Using Wayland display name 'wayland-0'
mag 14 12:12:30 Vultech gnome-shell[31015]: Unset XDG_SESSION_ID, getCurrentSessionProxy() called outside a user session. Asking logind directly.
mag 14 12:12:30 Vultech gnome-shell[31015]: Registering session with GDM
mag 14 12:12:30 Vultech gnome-shell[31015]: Will monitor session 7
mag 14 12:12:30 Vultech gnome-shell[31015]: Error looking up permission: GDBus.Error:org.freedesktop.portal.Error.NotFound: No entry for geolocation
mag 14 12:12:30 Vultech gnome-shell[31015]: Type GITypeInfo of property NM.Object::client does not match return type GITypeInfo of getter get_client. Falling back to slow path
mag 14 12:12:30 Vultech gnome-shell[31015]: Overwriting existing binding of keysym ff52 with keysym ff52 (keycode 6f).
mag 14 12:12:30 Vultech gnome-shell[31015]: Overwriting existing binding of keysym ff54 with keysym ff54 (keycode 74).
mag 14 12:12:31 Vultech gnome-shell[31015]: GNOME Shell started at Thu May 14 2026 12:12:30 GMT+0200 (Central European Summer Time)
mag 14 12:12:31 Vultech gnome-shell[31015]: Registering display with GDM
mag 14 12:12:31 Vultech gnome-shell[29293]: Shutting down GNOME Shell
mag 14 12:12:31 Vultech gnome-shell[29293]: Connection to xwayland lost
mag 14 12:12:31 Vultech gnome-shell[29293]: Gio.DBusError: GDBus.Error:org.freedesktop.DBus.Error.ServiceUnknown: The name is not activatable
                                            
                                            Stack trace:
                                              asyncCallback@resource:///org/gnome/gjs/modules/core/overrides/Gio.js:115:23
                                              _initializeUI/<@resource:///org/gnome/shell/ui/main.js:277:14
                                              
mag 14 12:12:31 Vultech gnome-shell[29293]: Using public X11 display :1024, (using unix:/tmp/.X11-unix/X1025 for managed services)
mag 14 12:12:51 Vultech gnome-shell[31015]: Received error from D-Bus search provider firefox.desktop: Gio.DBusError: GDBus.Error:org.freedesktop.DBus.Error.ServiceUnknown: The name is not activatable
mag 14 12:12:52 Vultech gnome-shell[31015]: Received error from D-Bus search provider firefox.desktop: Gio.DBusError: GDBus.Error:org.freedesktop.DBus.Error.ServiceUnknown: The name is not activatable
mag 14 12:12:53 Vultech gnome-shell[31015]: Invalid sequence for VSYNC frame info
mag 14 12:13:10 Vultech gnome-shell[31015]: meta_window_set_stack_position_no_sync: assertion 'window->stack_position >= 0' failed
mag 14 12:13:49 Vultech gnome-shell[31015]: Received error from D-Bus search provider firefox.desktop: Gio.DBusError: GDBus.Error:org.freedesktop.DBus.Error.ServiceUnknown: The name is not activatable
mag 14 12:13:50 Vultech gnome-shell[31015]: Received error from D-Bus search provider firefox.desktop: Gio.DBusError: GDBus.Error:org.freedesktop.DBus.Error.ServiceUnknown: The name is not activatable
mag 14 12:13:51 Vultech gnome-shell[31015]: meta_window_set_stack_position_no_sync: assertion 'window->stack_position >= 0' failed
mag 14 12:14:07 Vultech gnome-shell[31015]: meta_window_set_stack_position_no_sync: assertion 'window->stack_position >= 0' failed
mag 14 12:14:49 Vultech gnome-shell[31015]: meta_window_set_stack_position_no_sync: assertion 'window->stack_position >= 0' failed
mag 14 12:14:54 Vultech gnome-shell[31015]: meta_window_set_stack_position_no_sync: assertion 'window->stack_position >= 0' failed
mag 14 12:15:06 Vultech gnome-shell[31015]: meta_window_set_stack_position_no_sync: assertion 'window->stack_position >= 0' failed
mag 14 12:15:07 Vultech gnome-shell[31015]: meta_window_set_stack_position_no_sync: assertion 'window->stack_position >= 0' failed
mag 14 12:15:13 Vultech gnome-shell[31015]: meta_window_set_stack_position_no_sync: assertion 'window->stack_position >= 0' failed
mag 14 12:15:13 Vultech gnome-shell[31015]: meta_window_set_stack_position_no_sync: assertion 'window->stack_position >= 0' failed
mag 14 12:16:08 Vultech gnome-shell[31015]: Error: Wrong number of result metas returned by search provider org.gnome.Characters.desktop: expected 5 but got 0
                                            
                                            Stack trace:
                                              _ensureResultActors@resource:///org/gnome/shell/ui/search.js:240:19
                                              async*updateSearch@resource:///org/gnome/shell/ui/search.js:268:28
                                              _updateResults@resource:///org/gnome/shell/ui/search.js:862:27
                                              _doProviderSearch@resource:///org/gnome/shell/ui/search.js:710:24
                                              async*_doSearch/<@resource:///org/gnome/shell/ui/search.js:722:18
                                              _doSearch@resource:///org/gnome/shell/ui/search.js:720:25
                                              _onSearchTimeout@resource:///org/gnome/shell/ui/search.js:733:14
                                              _init/this.timeout_add_once/id<@resource:///org/gnome/gjs/modules/core/overrides/GLib.js:436:13
                                              @resource:///org/gnome/shell/ui/init.js:20:20
                                              
mag 14 12:16:08 Vultech gnome-shell[31015]: meta_window_set_stack_position_no_sync: assertion 'window->stack_position >= 0' failed
mag 14 12:16:10 Vultech gnome-shell[31015]: meta_window_set_stack_position_no_sync: assertion 'window->stack_position >= 0' failed
mag 14 12:16:10 Vultech gnome-shell[31015]: meta_window_set_stack_position_no_sync: assertion 'window->stack_position >= 0' failed
mag 14 12:16:10 Vultech gnome-shell[31015]: meta_window_set_stack_position_no_sync: assertion 'window->stack_position >= 0' failed
mag 14 12:16:11 Vultech gnome-shell[31015]: meta_window_set_stack_position_no_sync: assertion 'window->stack_position >= 0' failed
mag 14 12:16:11 Vultech gnome-shell[31015]: meta_window_set_stack_position_no_sync: assertion 'window->stack_position >= 0' failed
mag 14 12:16:13 Vultech gnome-shell[31015]: meta_window_set_stack_position_no_sync: assertion 'window->stack_position >= 0' failed
mag 14 12:16:41 Vultech gnome-shell[31015]: meta_window_set_stack_position_no_sync: assertion 'window->stack_position >= 0' failed
mag 14 12:16:41 Vultech gnome-shell[31015]: meta_window_set_stack_position_no_sync: assertion 'window->stack_position >= 0' failed
mag 14 12:19:22 Vultech gnome-shell[31015]: meta_window_set_stack_position_no_sync: assertion 'window->stack_position >= 0' failed
mag 14 12:19:56 Vultech gnome-shell[31015]: meta_window_set_stack_position_no_sync: assertion 'window->stack_position >= 0' failed
mag 14 12:20:29 Vultech gnome-shell[31015]: meta_window_set_stack_position_no_sync: assertion 'window->stack_position >= 0' failed
mag 14 12:20:37 Vultech gnome-shell[31015]: meta_window_set_stack_position_no_sync: assertion 'window->stack_position >= 0' failed
mag 14 12:21:07 Vultech gnome-shell[31015]: meta_window_set_stack_position_no_sync: assertion 'window->stack_position >= 0' failed
mag 14 12:21:51 Vultech gnome-shell[31015]: meta_window_set_stack_position_no_sync: assertion 'window->stack_position >= 0' failed
mag 14 12:22:37 Vultech gnome-shell[31015]: meta_window_set_stack_position_no_sync: assertion 'window->stack_position >= 0' failed
mag 14 12:22:39 Vultech gnome-shell[31015]: meta_window_set_stack_position_no_sync: assertion 'window->stack_position >= 0' failed

GNOME Shell version

gnome-shell 1:50.1-2

Forge version

89

Other installed/enabled extensions

[email protected]
  Name: AppIndicator and KStatusNotifierItem Support
  Description: Adds AppIndicator, KStatusNotifierItem and legacy Tray icons support to the Shell
  Path: /home/aton/.local/share/gnome-shell/extensions/[email protected]
  URL: https://github.com/ubuntu/gnome-shell-extension-appindicator
  Version: 64
  Enabled: Yes
  State: ACTIVE

[email protected]
  Name: Forge
  Description: Tiling and window manager for GNOME
- Please report bugs/issues on https://github.com/forge-ext/forge/issues
- Needs a new maintainer.
  Path: /home/aton/.local/share/gnome-shell/extensions/[email protected]
  URL: https://github.com/forge-ext/forge
  Enabled: Yes
  State: ACTIVE

[email protected]
  Name: Removable Drive Menu
  Description: A status menu for accessing and unmounting removable devices.
  Path: /usr/share/gnome-shell/extensions/[email protected]
  URL: https://gitlab.gnome.org/GNOME/gnome-shell-extensions
  Enabled: Yes
  State: ACTIVE

[email protected]
  Name: System Monitor
  Description: Monitor system from the top bar
  Path: /usr/share/gnome-shell/extensions/[email protected]
  URL: https://gitlab.gnome.org/GNOME/gnome-shell-extensions
  Enabled: Yes
  State: ACTIVE

Monitor Setup

Display (HannStar Display Corp 19"): 1280x1024 in 19", 60 Hz [External]
Display (Hewlett Packard 24"): 1920x1080 in 24", 60 Hz [External] *
Display (Philips 17S): 1280x1024 in 17", 60 Hz [External]

Other Notes

No response