Bug 511962

Summary: UI clicks are offset from pen position (but cursor is not) when using tablet and fractional scaling. Painting is unaffected.
Product: [Applications] krita Reporter: Stephen Albert-Moore <stephen.albert-moore>
Component: Tablets (tablet issues are only very rarely bugs in Krita!)Assignee: Krita Bugs <krita-bugs-null>
Status: RESOLVED LATER    
Severity: normal CC: halla
Priority: NOR    
Version First Reported In: 5.2.13   
Target Milestone: ---   
Platform: Ubuntu   
OS: Linux   
Latest Commit: Version Fixed/Implemented In:
Sentry Crash Report:

Description Stephen Albert-Moore 2025-11-11 16:47:46 UTC 
SUMMARY

With fractional scaling disabled, both painting and UI actions work as expected when using tablet input.
With fractional scaling in use, painting works as expected but UI clicks are offset from the cursor position.

STEPS TO REPRODUCE

1. Use a tablet with pen input as the primary display. "Clicks" with the pen work as expected in the OS UI.
2. In Ubuntu display settings, enable "Fractional Scaling" and set the scale to 133%.
3. Observe: pen "clicks" in the Ubuntu UI still work as expected.
4. Start Krita and create a new document. Maximize the window.
5. Select a brush and paint on the document. Observe: both the cursor and the drawn line match the pen position.
6. Hover the pen over the brush selector. The cursor matches the pen position.
7. Tap a brush icon with the pen.

OBSERVED RESULT

The actual selected brush is offset to the right and below.

EXPECTED RESULT

The actual selected brush is the one directly under the pen.

SOFTWARE/OS VERSIONS
Ubuntu 25.10 (default DE)
Linux 6.17.0

ADDITIONAL INFORMATION

The tablet is the primary display of the Framework 12 laptop. 
The pen is a Metapen M2 (MPP 2.0 protocol).

I suspect this has something to do with XWayland or Qt rather than Krita directly.
Comment 1 Halla Rempt 2025-11-11 17:49:22 UTC 
Yeah, there isn't much we can do about this on Linux. Dmitry has been fighting with wayland and scaling for the past couple of weeks, but the results will only be in master, not 5.2. And even then, the problem might intractable. I'm making this as LATER, because right now we cannot fix the problem.
Comment 2 Stephen Albert-Moore 2025-11-11 22:19:06 UTC 
(In reply to Halla Rempt from comment #1)
> Yeah, there isn't much we can do about this on Linux. Dmitry has been
> fighting with wayland and scaling for the past couple of weeks, but the
> results will only be in master, not 5.2. And even then, the problem might
> intractable. I'm making this as LATER, because right now we cannot fix the
> problem.

Thanks for the info, and thanks to Dmitry for the hard work!
Is there a more general issue tracking this Wayland scaling work?