SUMMARY Screen resolution gains additional 1px on wayland with fractional scaling. STEPS TO REPRODUCE 1. Log in with wayland session, 100% scaling. Verify that your screen resolution matches what's in Settings with `xrandr` (in my case 2560 x 1440) 2. Set 150% scaling. Again, verify your resolution to be identical with what's in settings with `xrandr` (still 2560 x 1440 for me) 3. Restart the machine or the session OBSERVED RESULT Settings will still show original resolution (2560 x 1440 in my case) while in fact it gained +1px horizontally which can be verified with `xrandr` that shows 2561 x 1440. EXPECTED RESULT Resolution should stay the same regardless of scaling. SOFTWARE/OS VERSIONS Distro: Kubuntu 23.10 KDE Plasma Version: 5.27.8 KDE Frameworks Version: 5.110.0 Qt Version: 5.15.10 Session: Wayland ADDITIONAL INFORMATION I also tried this with my second screen which is 2560 x 1600 and it got +1px both horizontally and vertically after restart. This is also quiet pronounced with gaming both natively and on proton - everything becomes blurry and the game sees this "extended" resolution along with the original one. Selecting either of those results in blur btw. Running the game when xrandr reports proper resolution results in crisp, pixel-perfect experience. There's a temporary solution - switch to 100% scale and then back to 150% and DON'T restart. It'll keep original resolution and it works fine. I also tried this with different fractional scaling like 120%, 140%, 170% and the result is the same. Unsurprisingly, scaling factors like 200% and 300% work fine. I'm not sure but this issue may be as well related to these: https://bugs.kde.org/show_bug.cgi?id=459373 https://bugs.kde.org/show_bug.cgi?id=475612 https://bugs.kde.org/show_bug.cgi?id=480171
The root cause is the same as Bug 480171, which has been investigated there and found to be a limitation in the upstream wayland protocol. It turns out unfortunately to be a somewhat complicated issue. Anyway, marking as a duplicate. *** This bug has been marked as a duplicate of bug 480171 ***
I don't think this is a duplicate. While the same sort of coordinate system conversion is the most likely root cause, Xwayland scaling doesn't go through fractional-scale-v1, so this can be fixed.
Bug 480171 isn't the one about XWayland.
Interesting thing to note is that everything is perfectly fine if you go and change scaling from 100% to anything in a live session. It's upon session start where additional 1px appears - it seems like when it tries to recalc screen size from local configs it has slightly different algo rather that calculating screen size from env vars during session run.
I can reproduce this bug in 5.27, but not in Plasma 6. So this is already fixed :)