SUMMARY I have a dual-screen setup with a 1920x1080 monitor and a 2560x1440 one. Unmaximised windows on the Full-HD monitor appear blurry. It has to be noted that no fractional scaling is applied. If I maximise the windows, the content are reproduced correctly. This applies to first-party KDE applications (e.g. System Settings) as well as to third-party ones (e.g. the unofficial Teams for Linux). STEPS TO REPRODUCE 1. ? OBSERVED RESULT Unmaximised windows are blurry. EXPECTED RESULT Unmaximised windows are not blurry. SOFTWARE/OS VERSIONS Linux: KDE neon KDE Plasma Version: 5.26.0 KDE Frameworks Version: 5.98.0 Qt Version: 5.15.6 ADDITIONAL INFORMATION
Upon further testing, it seems like moving the windows around makes the blurriness go away, while simply resizing them does not.
What placement mode are you using?
I'm using "Minimal overlapping". In the meantime, I have noticed that the blurriness does not depend on the screen the windows open on.
This seems to be the same issue happening in this Reddit post: https://reddit.com/r/kde/comments/yy6tjc/apps_get_blurry_when_minimizingsnapping_out_of/ I am experiencing the same issue on Arch Linux, currently Plasma 5.26.4 but it has been happening for awhile now, at least a couple of months probably longer. I think it started when I switched from an Nvidia to an AMD graphics card so that may be related. My scaling is set to 100% so there is no fractional scaling. I've tested and it happens in both X11 and Wayland mode if the apps use XWayland. Native Wayland apps seem to be fine. It also happens for both QT and GTK apps so it is not related to their individual scaling options/variables. I only have one 1440p monitor so it doesn't seem to be limited to multi-monitor setups either. SOFTWARE/OS VERSIONS Linux: Arch Linux KDE Plasma Version: 5.26.4 KDE Frameworks Version: 5.101.0 Qt Version: 5.15.7 Graphics Driver: mesa 22.3.1
Is there anything in the logs (journalctl --user -f -u plasma-kwin_wayland) when the blurriness appears?
Looks like there is a traceable error happening. This is as I maximized and un-maximized a window. thefeeltrain@archlinux ~> journalctl --user -f -u plasma-kwin_x11 Jan 04 07:27:07 archlinux kwin_x11[4470]: kwin_core: precision lost! floating value sent to X 542.662 Jan 04 07:27:07 archlinux kwin_x11[4470]: kwin_core: precision lost! floating value sent to X 90.2257 Jan 04 07:27:07 archlinux kwin_x11[4470]: kwin_core: precision lost! floating value sent to X 542.662 Jan 04 07:27:07 archlinux kwin_x11[4470]: kwin_core: precision lost! floating value sent to X 90.2257 Jan 04 07:27:07 archlinux kwin_x11[4470]: kwin_core: precision lost! floating value sent to X 513.662 Jan 04 07:27:07 archlinux kwin_x11[4470]: kwin_core: precision lost! floating value sent to X 80.2257 Jan 04 07:27:07 archlinux kwin_x11[4470]: kwin_core: precision lost! floating value sent to X 513.662 Jan 04 07:27:07 archlinux kwin_x11[4470]: kwin_core: precision lost! floating value sent to X 80.2257 Jan 04 07:27:07 archlinux kwin_x11[4470]: kwin_core: precision lost! floating value sent to X 392.662 Jan 04 07:27:07 archlinux kwin_x11[4470]: kwin_core: precision lost! floating value sent to X 146.226 Jan 04 07:27:31 archlinux kwin_x11[4470]: kwin_core: precision lost! floating value sent to X 365.662 Jan 04 07:27:31 archlinux kwin_x11[4470]: kwin_core: precision lost! floating value sent to X -45.7743
I see the same error message: Jan 04 16:20:47 Sleipnir kwin_x11[2528]: kwin_core: precision lost! floating value sent to X 947.833 Jan 04 16:20:47 Sleipnir kwin_x11[2528]: kwin_core: precision lost! floating value sent to X 326.269 It is worth noting that I am not using fractional scaling. I do not use Wayland, so I have no idea if this bug happens there as well or not. I am also using an AMD GPU.
It does happen in wayland, exact same error. But it only happens for XWayland applications. thefeeltrain@archlinux ~> journalctl --user -f -u plasma-kwin_wayland Jan 04 08:29:19 archlinux kwin_wayland[278267]: kwin_core: precision lost! floating value sent to X 297.553 Jan 04 08:29:19 archlinux kwin_wayland[278267]: kwin_core: precision lost! floating value sent to X 90.3611 This is with a librewolf window. If I run it with MOZ_ENABLE_WAYLAND=1 then the bug and error message is gone which is why I think it's purely an X11 issue. I looked into the error message and found a couple of other bugs with the same error, but they appear to be unrelated since they were fixed earlier while this bug persists into 5.26.5
5.27 introduces some changes that should fix this. Please reopen if this is still an issue.