Bug 355410

Please also refer to this post:
https://forum.kde.org/viewtopic.php?f=289&t=127279

Same issue here with plasma 5.5.3 on Fedora 23.

I'm also not sure that Plasma is to blame since this issue is also present in dolphin and kcm. Is this a bug in Qt?

Expected number of lines scrolled, working fine in:
* Qt5 applications like ksysguard 5.5.3, kwrite 15.08.3, konsole 15.08, most parts of KDE control center, KGpg
* Gtk2 and Gtk3 applications

Scrolls less than a single line per scroll wheel move in:
* Dolphin 15.08.1: Places panel, file list (central component), folders panel, but NOT terminal panel
* Plasma application overview (Application Dashboard in kdeplasma-addons)
* Plasma application starter
* Plasma indicator for removable devices (enable showing all devices in preferences to have enough devices to list)
* KDE control center, section window decoration designs

I have the exact same issue as Christian in comment 2, though I can't confirm if it's really the same one as comment 0. Many applications work fine but Dolphin and the application launcher have unbearably slow scrolling speeds.

Testing on Mageia Cauldron (6) with Plasma 5.5.4, Dolphin 15.12.1, Qt 5.6.0 beta.

Plasma-Desktop 5.6.1 and the problem continues.
on arch linux 
if i install xf86-input-libinput
    plasma5 mouse scroll is too slow. problem..

marking confirmed.  I strongly suspect this to be a Qt5 issue though (not a kde.org one)

*** Bug 358765 has been marked as a duplicate of this bug. ***

I have the same problem in dolphin scrolling the files (detail-list-view): one scroll-wheel event scrolls about half a row.

In KDE-Settings I have set it to 3 rows.

No such problems in konsole, mysql-query-browser (gtk2), eclipse (java-swt (gtk3))

Problem appeared since my last update (opensuse tumbleweed), only some minor kde5/qt5 upgrade.

Me too have this issue with mouse slow scrolling speed in dolphin and application launcher in Manjaro Linux Plasma 5, more info here: https://forum.manjaro.org/t/mouse-scrolling-speed-very-slow-in-dolphin-application-launcher/3853

Same issue on Debian - Plasma 5.6.4

This also occurs on Fedora 24. I can confirm this happens in a similar vein to comment 2 and comment 8.

Let me know if there is further information I can provide.

Fedora 24: Plasma 5.6.5, libinput 1.3.3, Dolphin 16.04.1, Qt 5.6.0

I can confirm for openSUSE Tumbleweed, Qt 5.6.1, Frameworks 5.24, Plasma 5.7 and KDE Apps 16.04.2

It can be fixed by replacing xf86-input-libinput to xf86-input-evdev(Arch Linux). Probably the same solution on other distros, but with another package names

I would not call that "fixed". One can workaround that problem by replacing, but it should work with libinput.

I confirm this. Delete xf86-input-libinput and install xf86-input-evdev solved problem.

I can confirm...
https://forum.antergos.com/topic/3390/mouse-wheel-scrolling-in-dolphin-and-wallpapers-list-is-slower-than-in-internet-browsers

"It can be fixed by replacing xf86-input-libinput to xf86-input-evdev(Arch Linux"

I've also Arch Linux and I've installed xf86-input-evdev; but however I have this problem for the left sidebar in dolphin (not for the main window), but only there. I could not find another application with this problem

I have the same problem on Arch Linux with xf86-input-evdev installed.

(In reply to Wulf from comment #16)
> "It can be fixed by replacing xf86-input-libinput to xf86-input-evdev(Arch
> Linux"
> 
> I've also Arch Linux and I've installed xf86-input-evdev; but however I have
> this problem for the left sidebar in dolphin (not for the main window), but
> only there. I could not find another application with this problem

"problem on Arch Linux with xf86-input-evdev " you needs manually uninstall xf86-input-libinput and it should work

@chermnykh2001: xf86-input-libinput is not installed, but I have this problem for dolphin left side panel; only there

(In reply to Rex Dieter from comment #5)
> marking confirmed.  I strongly suspect this to be a Qt5 issue though (not a
> kde.org one)

I'm wondering if this has been reported to QT folks?

https://www.qt.io/developers/

I'm not a developer and don't have an account there.

Changing the title as libinput on Wayland is *not* affected (and neither is xf86-input-evded, as already reported).

for me (and obviously other users too, comment 17) xf86-input-evdev is affected at dolphin left side panel

should I write a new bug report for this?

(In reply to Wulf from comment #22)
> for me (and obviously other users too, comment 17) xf86-input-evdev is
> affected at dolphin left side panel
> 
> should I write a new bug report for this?

There is already one: https://bugs.kde.org/show_bug.cgi?id=365968

QML scrolling with evdev works for me.

Reported upstream: https://bugreports.qt.io/browse/QTBUG-57186

*** Bug 372971 has been marked as a duplicate of this bug. ***

Is it a bug of Qt or KDE?

(In reply to Guo Yunhe (郭云鹤) from comment #26)
> Is it a bug of Qt or KDE?

Qt: https://bugreports.qt.io/browse/QTBUG-57186

It appears Qt guys won't fix it for Qt Quick Controls 1 since QQC2 is out without this bug. So the only solution is to port all of the QQC1 code to QQC2 just like you did for Kirigami. Or have wayland fully working which is not an easy route as well.

P.S. At this point i truly understand why RedHat doesn't go with Qt. It could be the best toolkit but if they aren't fixing bugs for your products it quickly becomes a pain.

Closing as duplicate of bug #375069 which has a better analysis of the issue. (https://bugreports.qt.io/browse/QTBUG-59261).

*** This bug has been marked as a duplicate of bug 375069 ***