Bug 471397

Summary:	Expose libinput's Mouse Wheel Emulation setting
Product:	[Applications] systemsettings	Reporter:	Yuri Gorshkov <me>
Component:	kcm_mouse	Assignee:	Plasma Bugs List <plasma-bugs-null>
Status:	CONFIRMED ---
Severity:	wishlist	CC:	cezary, natalie_clarius, nate
Priority:	NOR
Version First Reported In:	5.27.4
Target Milestone:	---
Platform:	openSUSE
OS:	Linux
Latest Commit:		Version Fixed/Implemented In:
Sentry Crash Report:
Attachments:	attachment-572176-0.html

Description Yuri Gorshkov 2023-06-23 17:18:52 UTC

SUMMARY
***
I'm using an Elecom EX-G trackball, which has a convenient extra button to scroll using the ball when held. I'm also using Wayland (I have two HiDPI displays with different resolutions, so I'm forced to apply different fractional scaling factors for each display).

Under GNOME, you can enable mouse wheel emulation with a dconf setting. When using X, this can be managed by setting libinput properties, or editing xorg.conf (if I remember correctly). KDE, however, doesn't have this setting exposed via the system settings, and Wayland doesn't have any official way to set properties that aren't supported  by the DE.

As a result, I can't have mouse wheel emulation when running KDE on Wayland.
***


STEPS TO REPRODUCE
1. Using KDE with Wayland, there is no mouse wheel emulation available.

OBSERVED RESULT
Using KDE with Wayland, there is no mouse wheel emulation available.

EXPECTED RESULT
Mouse wheel emulation works; one can scroll with the pointing device when holding a button, instead of using the wheel.
User can specify which button to use for initiating MW emulation.


SOFTWARE/OS VERSIONS
Windows: 
macOS: 
Linux/KDE Plasma: 5.27.4
(available in About System)
KDE Plasma Version: 
KDE Frameworks Version: 
Qt Version: 

ADDITIONAL INFORMATION

Comment 1 Yuri Gorshkov 2023-07-04 09:46:25 UTC

In command line, I can use the following:

  qdbus-qt5 org.kde.KWin /org/kde/KWin/InputDevice/$event org.kde.KWin.InputDevice.scrollButton 278
  qdbus-qt5 org.kde.KWin /org/kde/KWin/InputDevice/$event org.kde.KWin.InputDevice.scrollOnButtonDown true

Comment 2 Natalie Clarius 2023-09-15 15:58:10 UTC

By mouse wheel emulation you mean this https://wayland.freedesktop.org/libinput/doc/latest/scrolling.html#on-button-scrolling, right?

Comment 3 Yuri Gorshkov 2023-09-15 18:27:48 UTC

Created attachment 161645 [details]
attachment-572176-0.html

Correct. This is the mode to engage scrolling by holding a button and moving the mouse/ball.

On September 15, 2023 5:58:10 PM GMT+02:00, Natalie Clarius <bugzilla_noreply@kde.org> wrote:
>https://bugs.kde.org/show_bug.cgi?id=471397
>
>--- Comment #2 from Natalie Clarius <natalie_clarius@yahoo.de> ---
>By mouse wheel emulation you mean this
>https://wayland.freedesktop.org/libinput/doc/latest/scrolling.html#on-button-scrolling,
>right?
>
>-- 
>You are receiving this mail because:
>You reported the bug.

Comment 4 Cezary Drożak 2025-12-04 12:17:34 UTC

On GNOME I was also able to enable scroll button lock. With it, I was able to just press the forward button on my trackball once to scroll with the ball and the second time to return to normal mode.