[Issue]: Incorrect mouse buttons in Samsung DeX

[knyipab]

Describe the bug

When using hardware mouse with Samsung phone in DeX mode, the right click and middle click signals are not accurately sent (??) to sunshine. Some applications just cannot pick up user's middle click and right click. More specifically see below steps to reproduce.

This does not happen to the same phone in the normal, non-DeX mode.

Steps to reproduce

Test a Samsung phone with this website:
https://w3c.github.io/uievents/tools/mouse-event-viewer.html

This is in DeX mode (abnormal):

This is in normal, non-DeX mode:

This difference will causes applications below not able to respond to user mouse action correctly.

Affected games

Many applications. E.g.:

• Chromium cannot close tab using middle click
• FreeCAD cannot use middle click to navigate
• Onlyoffice (flatpak) cannot use right click to show menu

Other Moonlight clients

PC

Moonlight adjusted settings

No

Moonlight adjusted settings (please complete the following information)

Nope.

Moonlight default settings

Yes

Gamepad-related connection issue

No

Gamepad-related input issue

No

Gamepad-related streaming issue

Yes

Android version

Android 14 (One UI 6.1.1)

Device model

Samsung Z Fold5

Server PC OS version

Archlinux

Server PC GeForce Experience version

Sunshine v2025.122.141614

Server PC Nvidia GPU driver version

Intel in KVM

Server PC antivirus and firewall software

Nope

Screenshots

No response

Relevant log output

Additional context

No response