Bug 505710

Summary: Mouse cursor uncontrolled - clicks and hovering
Product: [Applications] systemsettings Reporter: Ivan Punko <punkoivan>
Component: kcm_touchpadAssignee: Plasma Bugs List <plasma-bugs-null>
Status: RESOLVED UPSTREAM    
Severity: grave CC: duha.bugs, natalie_clarius, nate
Priority: NOR    
Version First Reported In: 6.3.5   
Target Milestone: ---   
Platform: Arch Linux   
OS: Linux   
Latest Commit: Version Fixed/Implemented In:
Sentry Crash Report:
Attachments: mouse_jumps_uncontrolled

Description Ivan Punko 2025-06-17 19:47:13 UTC
Created attachment 182337 [details]
mouse_jumps_uncontrolled

SUMMARY
Mouse cursor uncontrolled - clicks and hovering, sometimes left and sometimes right button clicked and touchpad doesn't recognise and actual actions.
Filling it under Touchpad for a few reasons:
1. I had my mouse disconnected for the test purpose - nothing changed.
2. I managed to disable touchpad in system settings and that solved the issue.

STEPS TO REPRODUCE
1. In settings enable touchpad device;
2. Wait a few seconds;
3. Get described behaviour.

OBSERVED RESULT
Mouse cursor uncontrolled - clicks and hovering, sometimes left and sometimes right button clicked and touchpad doesn't recognise and actual actions.

EXPECTED RESULT
Touchpad just works.

SOFTWARE/OS VERSIONS

> Operating System: Arch Linux 
>KDE Plasma Version: 6.3.5
>KDE Frameworks Version: 6.15.0
>Qt Version: 6.9.1
>Kernel Version: 6.15.2-arch1-1 (64-bit)
>Graphics Platform: Wayland
>Processors: 16 × AMD Ryzen 7 PRO 4750U with Radeon Graphics
>Memory: 30.6 GiB of RAM
>Graphics Processor: AMD Radeon Graphics

ADDITIONAL INFORMATION
My first thought was like wayland is broken -> switched to X11 -> didn't help.
That bug occurred after updating the system with pacman.
I haven't found any information from pacman log that could be related, please let me know if I can search for a particular package.

>/var/log/pacman.log:[2025-06-17T11:08:24+0300] [ALPM] upgraded qt5-base (5.15.17+kde+r122-1 -> 5.15.17+kde+r123-1)
>/var/log/pacman.log:[2025-06-17T11:08:31+0300] [ALPM] upgraded kdeclarative (6.14.0-1 -> 6.15.0-1)
>/var/log/pacman.log:[2025-06-17T11:08:31+0300] [ALPM] upgraded kdeconnect (25.04.1-1 -> 25.04.2-1)
>/var/log/pacman.log:[2025-06-17T11:08:31+0300] [ALPM] upgraded kded (6.14.0-1 -> 6.15.0-1)
>/var/log/pacman.log:[2025-06-17T11:08:31+0300] [ALPM] upgraded kdenlive (25.04.1-1 -> 25.04.2-1)
>/var/log/pacman.log:[2025-06-17T11:08:31+0300] [ALPM] upgraded kdesu (6.14.0-1 -> 6.15.0-1)

Also converted screencast to gif attached.

Also consider this as a really critical bug for a person who doesn't own trackpoint or a spare mouse to disable touchpad.
Comment 1 Nate Graham 2025-06-18 15:03:55 UTC
It sounds like there's a problem with your touchpad. It could be a hardware issue, or it could be a software issue, or perpaps a combination of the two.

None of the code for this is in any KDE software, though; the action is all in the Libinput library. I'd encourage you to open a bug report about it at https://gitlab.freedesktop.org/libinput/libinput/-/issues/, and the maintainer there can hopefully help you figure out if it's a software issue in Libinput, or a physical problem with the device itself.

Good luck!
Comment 2 Ivan Punko 2025-06-18 16:18:03 UTC
Thanks, will do!