Steam Input stops working after using gamescope with --force-grab-cursor on Plasma X11

[matte-schwartz]

Your system information

• Steam client version (build number or date): 1726683985
• Distribution (e.g. Ubuntu): SteamOS 3.6.19
• Opted into Steam client beta?: No
• Have you checked for system updates?: Yes
• Steam Logs: steam-logs.tar.gz
• GPU: Advanced Micro Devices, Inc. [AMD/ATI] Sephiroth [AMD Custom GPU 0405] (rev ae)

Please describe your issue in as much detail as possible:

After launching a game on a Plasma X11 session using gamescope -f --force-grab-cursor -- %command% in the Steam Deck client, touch input stops working within the Steam client after the game is closed. I tested this on both Steam Deck OLED and ROG Ally, on SteamOS and upstream Arch, and both present this issue in the same way. Plasma Wayland seems unaffected.

Steps for reproducing this issue:

1. Launch a game (I used Grim Dawn and Hades II) with gamescope -f --force-grab-cursor -- %command% while on SteamOS Stable
2. Use the touchpad as a mouse for a few seconds once in-game, and tap the screen a couple times for good measure
3. Close the application
4. Attempt to use touch input within the Steam client after the game is fully closed

The cursor should disappear at this point, and start presenting weird behavior like dragging stuff as if you were holding down the touchpad. The behavior goes back to normal after restarting the Steam client.

I think this is a Steam client issue, although it's hard to say for sure given the additional factor of gamescope in the equation.