Bug 500075

Summary: Cursor speed is proportional to number of fingers in touchpad
Product: [Plasma] kwin Reporter: Santiago Cézar <santiagocezar2013>
Component: inputAssignee: KWin default assignee <kwin-bugs-null>
Status: RESOLVED UPSTREAM    
Severity: minor CC: duha.bugs, xaver.hugl
Priority: NOR    
Version First Reported In: 6.3.0   
Target Milestone: ---   
Platform: Fedora RPMs   
OS: Linux   
Latest Commit: Version Fixed/Implemented In:
Sentry Crash Report:

Description Santiago Cézar 2025-02-14 15:50:27 UTC 
SUMMARY
KWin (or libinput?) seems to take the sum of the individual finger speeds instead of the average, so when pressing down a touchpad (clickpad) with more than one finger, the cursor moves faster. This affects software with right/middle-click panning and using context menus with a single click, but it doesn't make them unusable though, just mildy annoying

STEPS TO REPRODUCE
1. Place more than one finger in the touchpad
2. Move the fingers in the same direction while pressing down the touchpad

OBSERVED RESULT
Cursor moves faster the more fingers you place

EXPECTED RESULT
Cursor moves at the same speed regardless of the finger amount

SOFTWARE/OS VERSIONS
Fedora Kinoite 41
KDE Plasma Version: 6.3.0
KDE Frameworks Version: 6.10.0
Qt Version: 6.8.2
Comment 1 Zamundaaa 2025-02-14 16:11:14 UTC 
Can confirm. KWin doesn't know how many fingers are down when you just move the cursor though, please report this at https://gitlab.freedesktop.org/libinput/libinput/-/issues
Comment 2 Santiago Cézar 2025-02-14 21:45:03 UTC 
Turns out this is actually intentional, according to this commit https://gitlab.freedesktop.org/libinput/libinput/-/commit/6664144611dce94ae42e0e88495d3955f5823de8

You're supposed to move only one finger instead of both, might open an issue anyways since there's probably a better solution to that