Mouse scroll to switch between tabs in KDE apps are broken

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1

I think this starts to happen very recently (< 3 days ago) I am not sure what might be wrong.
I am using CachyOS (converted from Archlinux by adding cachyos repository a while ago) with KDE Plasma 6.7.5 Wayland / KDE Frameworks 6.30.0 / Qt 6.12.0.

I can no longer switch tab by mouse scrolling in tab bar in Konsole / Dolphin / Kate, and it continues to work with Firefox tab switching, web browsing, and works in text edit area of Kate.

Did anyone else starts encounter this recently? or find out what might be wrong?

2

This is a weird bug, possibly Wayland- or KDE-specific? When using KDE Wayland, I can’t scroll my open Dolphin tabs, but when in Openbox (which is X11), I can.

3

After reviewing by system log, I find out Qt is upgraded from 6.11.2 to 6.12.0 recently, but I am afraid to downgrade these packages because other programs might already be re-compiled for this Qt version, so I am not very sure but looks very likely.

4

@axzxc1236 You would likely need to downgrade dozens of packages and not update for month or so until the next KDE Gear release.

Probably not worth it for this issue alone, unless you have several issues, and even then, there are likely to be bug fixes in between that from KDE Frameworks.

In the meantime, submitting bug reports at bugs.kde.org help.

5

Do you happen to know which component this function might belong to? There is too many categories I feel overwhelmed just looking at them.

6

For this, there is nothing specific to Dolphin tabs, so choose “general”.
To confirm, you should be at: https://bugs.kde.org/enter_bug.cgi?product=dolphin
And then, like you said, “Component” > general.

7

With Arch this is a completely unsupportable state.

But yes, I hadn’t noticed until you mentioned it - but I can’t scroll tabs in Manjaro either.

I tend to use Alt to select tabs or just click.

8

I opened an issue in Dolphin bug tracker

9

In Plasma / Wayland setups with recent Qt 6 releases, mouse wheel tab switching issues usually stem from wheel event routing or changes in Qt’s QTabBar scroll event handling.

A few things to check:

  1. Check System Settings → Mouse & Touchpad → Mouse settings to see if scroll direction or wheel resolution/emulation options were reset.
    1. In applications like Kate and Dolphin, inspect application-specific settings (Configure Dolphin → General, or Configure Kate → Appearance/Tabs) to verify whether “Switch tabs on scrolling” or tab switching options remain enabled.
    1. Check KWin window rules or shortcut configuration in System Settings → Window Management → Window Rules to ensure no global mouse wheel or modifier override is intercepting scroll events over client decorations.
    1. Since Qt 6.12.0 changed some high-resolution scroll wheel event dispatching on Wayland, running Kate or Dolphin with QT_QPA_PLATFORM=xcb via Xwayland (if available) can confirm whether the issue is strictly isolated to the Wayland QPA backend.
10

A guy left a detailed explaination on bug tracker tracking this down to Qt’s regression, link relavant Qt git commit, and provide PKGBUILD they modified, I can vouch for that patch.

11

A bit of AI slop coming in here… please don’t waste time posting anything you don’t check.

I spot it a mile away, when AI says ‘look for this or that’ it obviously isn’t a human who actually went in settings and looked.

Overall, then, I guess the most prudent option is to wait for a fix to come through the pipes. I remember this happened a few years ago due to changes in the underlying frameworks.