Muffin loses keyboard focus after IBus restart (triggered by cache reset) until Cinnamon is restarted

Distribution

Mint 22.3

Package version

Cinnamon 6.6.7

Graphics hardware in use

Intel Arrow Lake‑U (Gen 15) Integrated Graphics

Frequency

Always

Bug description

When IBus restarts mid‑session (such as after clearing its cache), Muffin loses the active keyboard input surface. After this occurs, no application receives keyboard events until Cinnamon is restarted with cinnamon --replace or the session is fully logged out and back in.

This appears to be a focus‑routing failure in Muffin triggered by an input‑method restart.

Steps to reproduce

1. Start a normal Cinnamon session.

2. Open any terminal emulator (gnome‑terminal, xterm, tilix — all behave the same).

3. Clear the IBus cache: rm -rf ~/.cache/ibus

4. Restart IBus (or let it restart automatically):

5. Return to the terminal and attempt to type.

Expected behavior

Muffin should correctly rebind the active input surface after an IBus restart. Keyboard events should continue to route to the focused window without requiring a Cinnamon restart.

Additional information

This occurs on a clean Linux Mint installation with default Cinnamon settings.
It is reproducible across multiple systems and hardware configurations.
The issue is not caused by Stacer, BleachBit, or any third‑party cache cleaners.
The trigger is specifically IBus restarting mid‑session, which should be handled gracefully by the compositor.
The fact that cinnamon --replace immediately restores keyboard input strongly suggests the issue is in Muffin’s focus or input‑routing logic.

Reproduce the issue by clearing ~/.cache/ibus, restarting IBus, and checking whether keyboard input returns after cinnamon --replace. Start in Muffin's focus or input-routing logic and verify that keyboard events continue reaching the focused window after an IBus restart without restarting Cinnamon.