Public bug reported:

I'm experiencing a more severe manifestation of this
[https://bugs.launchpad.net/ubuntu/+source/gnome-shell-extension-ubuntu-
dock/+bug/1857392] bug: not just log warnings, but complete keyboard
input corruption after a secondary HID keyboard device sends a modifier
combo. This took about 2 days to diagnose, and as DVV has noted, I was
artificially assisted.

Hardware: Roccat Tyon gaming mouse (USB ID 1e7d:2e4b). It exposes 4 HID
interfaces to the kernel, including a full keyboard device (interface 1,
input4, handlers: sysrq kbd event4 leds). Certain mouse buttons send
keyboard macros via this HID keyboard interface — e.g. Ctrl+W for close-
tab in Firefox.

Symptom: After login, pressing the mouse button that sends Ctrl+W via
the HID keyboard interface causes keyboard input to become corrupted for
all Wayland clients. Modifiers get lost or stuck, keys produce wrong
characters, and the keyboard remains broken until logout. The
"Overwriting existing binding" warnings appear in the journal at the
same time.

Key finding: Disabling and re-enabling all GNOME Shell extensions that
register keybindings via Main.wm.addKeybinding() immediately fixes the
corruption. This forces GNOME Shell to call removeKeybinding() +
addKeybinding(), which re-resolves key combos against the current keymap
and flushes the stale state.

Extensions that register keybindings on my system:
- [email protected]
- gTile@vibou
- [email protected]
- [email protected]

Bisection result: A fresh test user account with no extensions enabled
does NOT experience the bug. Disabling all four keybinding extensions
prevents the bug. Re-enabling them after a disable cycle produces clean
keybinding state and the bug does not trigger.

Current workaround: An autostart script that waits 3 seconds after
login, then disables and re-enables all four keybinding extensions. This
consistently prevents the corruption but has a timing window — pressing
the Roccat button before the script completes still triggers the bug.

Re: MR#4816: The proposed fix removes the warning message but doesn't
address the underlying keybinding resolution corruption that causes
actual keyboard input breakage with secondary HID keyboard devices.

Journal excerpt from a session where the bug triggered (reboot, before 
workaround script ran):
Feb 09 14:44:34 gnome-shell: Overwriting existing binding of keysym ffb3 with 
keysym ff9b (keycode 59).
Feb 09 14:44:34 gnome-shell: Overwriting existing binding of keysym ffb9 with 
keysym ff9a (keycode 51).
Feb 09 14:44:38 gnome-shell: Overwriting existing binding of keysym ff9a with 
keysym ffb9 (keycode 51).
Feb 09 14:44:38 gnome-shell: Overwriting existing binding of keysym ffb3 with 
keysym ff9b (keycode 59).
Feb 09 14:44:39 gnome-shell: Overwriting existing binding of keysym ff9a with 
keysym ffb9 (keycode 51).
Feb 09 14:44:39 gnome-shell: Overwriting existing binding of keysym ff9b with 
keysym ffb3 (keycode 59).

Roccat Tyon HID device enumeration (/proc/bus/input/devices):
N: Name="ROCCAT ROCCAT Tyon White Mouse"
H: Handlers=mouse0 event2 (standard mouse)

N: Name="ROCCAT ROCCAT Tyon White Consumer Control"
H: Handlers=kbd event3 (media keys)

N: Name="ROCCAT ROCCAT Tyon White"
H: Handlers=sysrq kbd event4 leds (keyboard emulation - sends Ctrl+W)

N: Name="ROCCAT ROCCAT Tyon White"
H: Handlers=event5 js0 (analog stick)


System info:
- Ubuntu 25.10, Wayland session
- GNOME Shell 49.0-1ubuntu1.2
- Mutter 49.0-2ubuntu5.3
- libxkbcommon 1.7.0-2.1
- xkb-data 2.42-1ubuntu1
- Kernel 6.17.0-12-generic
- Keyboard layout: gb+extd

Related upstream issues:
- GNOME Mutter #554 (keybinding overwrite warnings with multiple devices)
- GNOME Shell #5890 (wrong key when multiple events combined in single 
SYN_REPORT)
- GNOME Shell #208 (modifier key not taken into account when typing too fast)
- Hyprland #9318 (same bug class in a different Wayland compositor: 
programmable mouse HID keyboard breaks layout)

** Affects: gnome-shell-extension-ubuntu-dock (Ubuntu)
     Importance: Undecided
         Status: New


** Tags: questing

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https://bugs.launchpad.net/bugs/2141375

Title:
  keyboard input corruption after HID keyboard sends modifier combo

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