Bug 512053 - Pointer speed affects scroll speed
Summary: Pointer speed affects scroll speed
Status: RESOLVED WORKSFORME
Alias: None
Product: kwin
Classification: Plasma
Component: input (other bugs)
Version First Reported In: 6.5.2
Platform: Fedora RPMs Linux
: NOR normal
Target Milestone: ---
Assignee: KWin default assignee
URL:
Keywords:
Depends on:
Blocks:
 
Reported: 2025-11-14 00:44 UTC by Aida
Modified: 2025-12-14 03:46 UTC (History)
2 users (show)

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Description Aida 2025-11-14 00:44:50 UTC 
SUMMARY
Changing the pointer speed changes the scroll speed in an unexpected way.

STEPS TO REPRODUCE
1. Use a mouse with an ordinary 15 degree detent scroll wheel
2. Set scroll factor to 1 and pointer speed to 0.5
3. Open wev or another tool to view wayland events

OBSERVED RESULT
Each scroll event reports an angle of 22 degrees

EXPECTED RESULT
Each scroll event reports an angle of 15 degrees as it does when the pointer speed is set to 0

SOFTWARE/OS VERSIONS
Linux/KDE Plasma: Fedora Linux 43 KDE Plasma Desktop Edition
KDE Plasma Version: 6.5.2
KDE Frameworks Version: 6.19.0
Qt Version: 6.10.0
Comment 1 David Edmundson 2025-11-14 10:17:37 UTC 
I can't reproduce and I'm confident we don't change anything at a KDE level. Can you double check  your scroll speed was on exactly 1.

Can you open the kwin debug tool (search for "kwin debug")   and look under input devices, this is the data we get from libinput.
Comment 2 Aida 2025-11-14 19:52:21 UTC 
(In reply to David Edmundson from comment #1)
> I can't reproduce and I'm confident we don't change anything at a KDE level.
> Can you double check  your scroll speed was on exactly 1.
> 
> Can you open the kwin debug tool (search for "kwin debug")   and look under
> input devices, this is the data we get from libinput.

The kwin debug console says the scroll factor is 1 but I still get the behaviour. libinput debug-events shows expected behaviour but the input events in the kwin debug console show the odd behaviour. I have a laptop running fedora 42 and I couldn't reproduce it on that so I wonder if something broke in fedora 43.
Comment 3 Aida 2025-11-14 21:21:22 UTC 
I've done a bit more testing and found that:
It only occurs when pointer acceleration is turned off.
It does not occur on the Fedora 43 KDE live image running in QEMU.
It occurs with every mouse I connect to my computer.
Comment 4 Bug Janitor Service 2025-11-29 03:46:10 UTC 
🐛🧹 ⚠️ This bug has been in NEEDSINFO status with no change for at least 15 days. Please provide the requested information, then set the bug status to REPORTED. If there is no change for at least 30 days, it will be automatically closed as RESOLVED WORKSFORME.

For more information about our bug triaging procedures, please read https://community.kde.org/Guidelines_and_HOWTOs/Bug_triaging.

Thank you for helping us make KDE software even better for everyone!
Comment 5 Bug Janitor Service 2025-12-14 03:46:15 UTC 
🐛🧹 This bug has been in NEEDSINFO status with no change for at least 30 days. Closing as RESOLVED WORKSFORME.