Bug 500309 - Some apps don't recognize drawing tablet inputs after upgrading to Plasma 6.3.0
Summary: Some apps don't recognize drawing tablet inputs after upgrading to Plasma 6.3.0
Status: RESOLVED INTENTIONAL
Alias: None
Product: kwin
Classification: Plasma
Component: input (other bugs)
Version First Reported In: 6.3.0
Platform: Arch Linux Linux
: NOR normal
Target Milestone: ---
Assignee: KWin default assignee
URL:
Keywords: regression
: 500464 501992 (view as bug list)
Depends on:
Blocks:
 
Reported: 2025-02-18 11:13 UTC by JadenJSJ
Modified: 2025-03-25 21:06 UTC (History)
6 users (show)

See Also:
Latest Commit:
Version Fixed In:
Sentry Crash Report:


Attachments
Updated packages (11.75 KB, text/x-log)
2025-02-18 11:13 UTC, JadenJSJ
Details

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Description JadenJSJ 2025-02-18 11:13:49 UTC
Created attachment 178511 [details]
Updated packages

SUMMARY
Some apps like Chrome/Thorium is not aware that my cursor is hovering over it, and can't drag and drop in apps such as dolphin. (works normally when using a mouse)
This issue cropped up when upgrading to Plasma 6.3.0 which is supposed to be somewhat of a tablet overhaul, so I guess it is pretty natural to suspect it.

After rolling back to a previous snapshot of root, my tablet worked on Chrome again.

STEPS TO REPRODUCE
1. Upgrade whole rolling release to Plasma 6.3.0 and related packages to 6.3.0
2. Use wayland
3. Open Chrome & Drag and drop in apps like Dolphin

OBSERVED RESULT
Chrome/Thorium is not aware that my cursor is hovering over it or that I’m clicking on it with my tablet and shows a plus cursor or sometimes the normal pointer.
Sometimes after focusing Chrome the tablet stops being able to click on anything (even switching to other apps).
(Focus chrome, then alt tab to dolphin for example, dolphin does not recognize the tablet like in Chrome.) (Sometimes the plus cursor also shows up on other applications when this happens)
Until the new focused application is clicked with a mouse or trackpad.

I also noticed that I can't drag and drop in apps like dolphin with the tablet, it only selects it.

EXPECTED RESULT
Tablet works normally like a mouse in all applications.

SOFTWARE/OS VERSIONS
System Information:
Operating System: Arch Linux
KDE Plasma Version: 6.3.0
KDE Frameworks Version: 6.11.0
Qt Version: 6.8.2
Kernel Version: 6.6.72-native_intel-xanmod1-1-lts (64-bit) # (Not relevant to this issue)
Graphics Platform: Wayland
Drawing Tablet: Huion Inspiroy RTS-300

ADDITIONAL INFORMATION
Things I’ve tried so far (that haven’t worked):

Change chrome flags:
Preferred Ozone platform
Selects the preferred platform backend used on Linux. “Auto” selects Wayland if possible, X11 otherwise. – Linux
#ozone-platform-hint
To X11

Revert wacomtablet to older version
wacomtablet (6.2.5-1 → 6.3.0-1)

Revert to previous kernel patch version
linux-xanmod-lts (6.6.65-1 → 6.6.72-1)

Packages known to NOT cause the breakage: linux*, wacomtablet, libx11, xkeyboard-config, xorg-xwayland, libxkbcommon, libxkbcommon-x11, hwdata

I have tried upgrading the packages above and my tablet still works fine in Chrome.

I have attached pacman.trimmed.log which lists all the packages I've updated.
They are the packages that may have caused the breakage.
Comment 1 JadenJSJ 2025-02-18 11:16:56 UTC
Also doesn't look like I'm the only one with this problem.
Someone else using a XPPen drawing display tablet has the same issue as me, and is also running Plasma 6.3.0.

https://discuss.kde.org/t/xp-pen-artist-12-tablet-issues-on-kde-neon-wayland-click-not-registering-in-certain-apps/30083
Comment 2 David Redondo 2025-02-18 15:13:31 UTC
KWin 6.3 removed pointer emulation for tablets 

https://invent.kde.org/plasma/kwin/-/commit/f22a04171b3de82f7ed0059bc15c4084dd07161e
Comment 3 Vlad Zahorodnii 2025-02-18 15:37:23 UTC
chrome doesn't support tablet input when running with wayland support. also, note that wayland support in chrome is considered incomplete. you can work around it by running chrome as an X client (this should be the default too).

you can also set the KWIN_WAYLAND_EMULATE_TABLET=1 environment variable, but I should warn that it will be removed in the future.
Comment 4 Vlad Zahorodnii 2025-02-18 15:40:30 UTC
> “Auto” selects Wayland if possible, X11 otherwise. – Linux

is new though
Comment 5 duha.bugs 2025-02-20 17:13:25 UTC
*** Bug 500464 has been marked as a duplicate of this bug. ***
Comment 6 Antonio Rojas 2025-03-25 18:25:56 UTC
*** Bug 501992 has been marked as a duplicate of this bug. ***
Comment 7 Alexandr Podgorniy 2025-03-25 19:08:01 UTC
It's very sad that KDE developers want to get rid of it. MPV and Chromium developers has no intent to fix this bug on their side, this bug is few years old for both chromium and mpv, and that KDE workaround was very handy, because it provided consistent tablet experience on wayland. What is the most ironic thing about 6.3 update - it says that tablet experience has been improved, but at the same time it was downgraded drastically, since now it's impossible to use discord with tablet, and draw on separate window. Now i have to constantly switch between mouse and tablet only to use discord while drawing, which is very inconvenient.

Dear developers, please, don't get rid of this workaround. Can it be implemented as separate setting in tablet settings?
Comment 8 Vlad Zahorodnii 2025-03-25 20:32:28 UTC
It's deprecated for technical reasons.

I can't speak for MPV (I haven't found any issue about it; has it even been reported to them?), but I haven't heard of Chromium developers actually rejecting the idea of supporting the tablet-v2 protocol, the relevant ticket is still open.
Comment 9 Vlad Zahorodnii 2025-03-25 20:48:53 UTC
(In reply to David Redondo from comment #2)
> KWin 6.3 removed pointer emulation for tablets 
> 
> https://invent.kde.org/plasma/kwin/-/commit/
> f22a04171b3de82f7ed0059bc15c4084dd07161e

https://invent.kde.org/plasma/kwin/-/commit/25c65abddd95eb87fb892a8594faccbf509ff62f is the relevant commit just in case.
Comment 10 Alexandr Podgorniy 2025-03-25 21:06:19 UTC
Honestly, I don't believe that chromium developers will actually fix the issue. Issue is 2 years old, + they ignore other input issues for even longer, like libinput kinetic scrolling. I understand that emulating mouse isn't the best solutions, i encountered some bugs with double clicks that you mentioned, but ability to use Discord with tablet outweighed all other issues in my case. Speaking of mutter, they indeed never supported this kind of workarounds, but that's one of the reasons why i switched from Gnome to KDE, because tablet just works in every app. Maybe it should be resolved without relying on kwin workaround, but i don't know how.