[Bug]: Cursor offset in OpenRA on Ubuntu 26.04 LTS with Cinnamon and 150% display scaling

[rpunselie]

What happened?

OpenRA has a cursor offset issue on Ubuntu 26.04 LTS when running under Cinnamon with fractional display scaling enabled. The mouse cursor position does not match the actual UI interaction point.

The visible cursor appears shifted relative to the OpenRA user interface. In my case, the effective click/hover position is offset up and to the left from where the cursor is displayed, making menus and in-game UI elements difficult to interact with accurately.

This issue occurs in both the latest release build and the current playtest build.

Environment:

OS: Ubuntu 26.04 LTS
Desktop environment: Cinnamon
Display: Laptop screen, 2560×1600
Display scaling: 150%
OpenRA version: Release and playtest builds both affected

Steps to reproduce:

1. Start Ubuntu 26.04 LTS with Cinnamon.
2. Use a laptop display with resolution 2560×1600.
3. Enable 150% display scaling.
4. Launch OpenRA.
5. Move the mouse over menus or UI elements.
6. Try to click buttons or interact with the interface.

What should have happened?

The visible mouse cursor should align with the actual UI hover/click position.

Actual result:

The cursor is offset from the UI interaction point. The effective click/hover position appears up and to the left of the visible cursor position, so UI elements are not selected or clicked where expected.

Output of snap info $snap_name

AppImage

Output of snap connections $snap_name

AppImage

Output of snap version

AppImage

Relevant log output

Teminal output of app

Platform is Linux (X64)
Engine version is release-20250330
Runtime: .NET CLR 6.0.36
Using SDL 2 with OpenGL (Modern) renderer
Desktop resolution: 2560x1600
No custom resolution provided, using desktop resolution
Using resolution: 2560x1600
Using window scale 2.00
OpenGL renderer: Mesa Intel(R) Iris(R) Xe Graphics (RPL-P)
OpenGL version: 4.6 (Core Profile) Mesa 26.0.3-1ubuntu1
Using default sound device
Internal mods:
	ra (release-20250330)
	ra-content (release-20250330)
External mods:
	ra-release-20250330 (release-20250330)
Loading mod: ra