[Bug 58653] New: winewayland: Mouse pointer locking fails with extreme camera sensitivity in 3D applications when using fractional scaling on GNOME/Wayland

[WineHQ Bugzilla]

http://bugs.winehq.org/show_bug.cgi?id=58653

Bug ID: 58653
           Summary: winewayland: Mouse pointer locking fails with extreme
                    camera sensitivity in 3D applications when using
                    fractional scaling on GNOME/Wayland
           Product: Wine
           Version: unspecified
          Hardware: x86-64
                OS: Linux
            Status: UNCONFIRMED
          Severity: normal
          Priority: P2
         Component: winewayland
          Assignee: [e-mail]
          Reporter: [e-mail]
      Distribution: ---

Created attachment 79230
  --> http://bugs.winehq.org/attachment.cgi?id=79230
Demonstration of failed mouse lock and extreme sensitivity with 150% fractional
scaling enabled.

When running a 3D application (in this case, Roblox Studio) using the
winewayland driver, the mouse pointer fails to lock to the window when it
should (e.g., holding right-click to pan the camera). This also causes the
camera to move at an extremely high and uncontrollable speed.

This issue only occurs when fractional scaling is enabled in the host Linux
desktop environment (e.g., 150% scaling on GNOME). The bug is not present when
using integer scaling factors like 100% or 200%.

Changing the screen DPI setting within winecfg does not fix or mitigate the
issue when fractional scaling is active.

Steps to Reproduce:

1. Use a Linux desktop environment on Wayland (e.g., GNOME on Fedora 42).

2. Enable fractional scaling in the display settings (e.g., 150%).

3. Run a 3D application that uses relative mouse motion and requires
pointer locking (e.g., Roblox Studio).

4. In the application's 3D viewport, perform the action to lock the mouse
and pan the camera (e.g., hold the right mouse button).

5. Move the mouse.

Actual Results:
The mouse cursor does not lock or hide. It remains visible and can move outside
the application window. Any small mouse movement causes the in-game camera to
spin around at an uncontrollably high velocity.

Expected Results:
The mouse cursor should lock (become confined to the window) and hide. Mouse
movements should translate to smooth and controllable camera panning at a
normal sensitivity. This expected behavior occurs correctly when system display
scaling is set to 100% or 200%.

System Information:

OS: Fedora Linux 42

Kernel Version: 6.15.9-201.fc42.x86_64

Display Server: Wayland (GNOME)

CPU: AMD Ryzen 9 7940HS

GPU: AMD Radeon RX 7700S [Discrete] / AMD Radeon 780M [Integrated]

Memory: 27.20 GiB

Additional Notes:
This bug was reproduced while running Roblox Studio via the Vinegar Flatpak
project, which utilizes Wine. The issue appears to be independent of the
application itself and points to a problem in how the winewayland driver
handles pointer coordinates and locking events when the Wayland compositor is
using a fractional scale factor.

[Bug 58653] winewayland: Mouse pointer locking fails with extreme camera sensitivity in 3D applications when using fractional scaling on GNOME/Wayland

[WineHQ Bugzilla]

http://bugs.winehq.org/show_bug.cgi?id=58653

--- Comment #1 from [e-mail] ---
Created attachment 79231
  --> http://bugs.winehq.org/attachment.cgi?id=79231
Demonstration of correct mouse lock behavior after switching system display
scaling to 100%.