https://bugs.kde.org/show_bug.cgi?id=521964
Bug ID: 521964
Summary: Plasma: KDE Plasma: desktop and wallpaper, panels and
widgets, launcher menu, lock and login screens, Breeze
theme, the KWin window manager, networking, audio, and
Bluetooth support, KDED modules, and other integral
components of Plasma Breeze Breeze (ar
Classification: Plasma
Product: kwin
Version First unspecified
Reported In:
Platform: CachyOS
OS: Linux
Status: REPORTED
Severity: normal
Priority: NOR
Component: wayland-generic
Assignee: [email protected]
Reporter: [email protected]
Target Milestone: ---
Created attachment 193512
--> https://bugs.kde.org/attachment.cgi?id=193512&action=edit
on my 2k monitor and any application the drop down menus are forced and
aritfact on my 4k monitor.
DESCRIPTION
Dropdown menus and context menus appear completely unanchored from the window
(at the top of the screen) and on the wrong monitor, when using fractional
scaling with mismatched physical monitor resolutions and a vertical offset on
NVIDIA + KWin Wayland.
STEPS TO REPRODUCE
1. Set up two monitors with different physical resolutions, different scale
factors, and a vertical offset. My exact layout:
- DP-3 (4K 3840x2160): geometry 0,130 2560x1440 @1.5x
- DP-1 (1440p 2560x1440): geometry 2560,0 2560x1440 @1x
2. Open any Qt/KDE app with a menu bar (Dolphin, Konsole, Kate) on either
monitor.
3. Click any dropdown menu (File, Edit, View, etc.) or right-click for a
context menu.
OBSERVED RESULT
Menus appear at screen position ~0,0 (outside the window entirely — not
anchored below the clicked button). If the app window is on the 1440p monitor,
the menu additionally renders on the 4K monitor instead. Both symptoms happen
simultaneously. A black bar artifact also appears on window edges on the 4K
monitor. Identical behaviour with native Wayland Qt apps and XWayland apps
(QT_QPA_PLATFORM=xcb), confirming KWin's compositor-level popup mapping is the
root cause. Removing panels does not help. No kwin_core token errors in
journalctl.
EXPECTED RESULT
Menus appear below the clicked menu bar entry, inside the window, on the
monitor where the window is located.
SOFTWARE/OS VERSIONS
Operating System: CachyOS, Linux 7.0.12-1-cachyos
KDE Plasma Version: 6.7.0
KDE Frameworks Version: 6.12.0
Qt Version: 6.11.1 (qt5-wayland: 5.15.19+kde+r55, KDE-patched)
ADDITIONAL INFORMATION
- Issue is persistent from boot, not triggered by hotplug — distinguishes from
Bug 516185/516422.
- wl_output reports integer scale 2 for the 4K monitor (ceiling of 1.5x
fractional). XWayland uses this integer scale, and KWin's popup coordinate
translation between differently-scaled outputs produces wrong results.
- The xx-fractional-scale-v2 protocol is compiled into KWin 6.7.0 but not
advertised to clients — only wp_fractional_scale_manager_v1 is exposed.
- NVIDIA RTX 4070 Ti SUPER, driver 610.43.02 (proprietary). This driver
introduced a new DRM color pipeline (nvidia_drm.color_pipeline=1) with known
KWin compatibility issues (pageflip timeouts, compositor instability reported
on NVIDIA Developer forums).
- Related: Bug 490919 (same on RTX 4080 SUPER, incorrectly closed DOWNSTREAM),
Bug 516434 (duplicate of 516185, hotplug-only, not this).
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