Hi - for what it's worth, I can't reproduce on Fedora KDE 41 - which still has Qt 6.8.2, possibly related?

Cannot reproduce with git master plasma-systemmonitor but Qt 6.8.2. Could be a Qt 6.9 regression.

I see this bug in Fedora 42 (Qt 6.9.0), but not in Plasma built from git-master (Qt 6.8.2)
There's a duplicate from someone who also has Qt 6.9.0

*** Bug 503226 has been marked as a duplicate of this bug. ***

Created attachment 180654 [details]
misplaced context menu after right-click on a column in "Overview" page

Same bug after right-click on a column in "Overview" page.

Operating System: Arch Linux 
KDE Plasma Version: 6.3.4
KDE Frameworks Version: 6.13.0
Qt Version: 6.9.0
Graphics Platform: Wayland

A possibly relevant merge request was started @ https://invent.kde.org/plasma/plasma-systemmonitor/-/merge_requests/356

*** Bug 504063 has been marked as a duplicate of this bug. ***

Git commit df7f22ab23499c6a8851b3b3262d4294925a401f by Arjen Hiemstra.
Committed on 12/05/2025 at 10:08.
Pushed by ahiemstra into branch 'master'.

faces/*table: Fix positioning of context menus with Qt >= 6.9

Not entirely sure how behaviour changed here but popups ended up
incorrectly positioned with newer Qt.

M  +4    -2    src/faces/applicationstable/contents/ui/FullRepresentation.qml
M  +4    -2    src/faces/processtable/contents/ui/FullRepresentation.qml

https://invent.kde.org/plasma/plasma-systemmonitor/-/commit/df7f22ab23499c6a8851b3b3262d4294925a401f

*** Bug 504096 has been marked as a duplicate of this bug. ***

*** Bug 504140 has been marked as a duplicate of this bug. ***

Hi,
i'm testing with 
plasma-systemmonitor-6.3.80~16.git7f7856f-1.fc42.x86_64

and the problem is still not resolved (although the 'fix' is in the commit-history?)`

It's fixed for me with that commit, also on Fedora 42. I would suspect a packaging issue with that package, unless you're still using Qt 6.8.x for some reason, in which case that's why.

sorry to say, but no - not fixed... completely :-)

It works on a single-screen or on a multi-screen-setup if you are on the main-screen: Here for example, if opening system-monitor window on the laptop-screen (with additional +4K monitor)

If you call system-monitor on the 4K screen, then it's still broken (see attachments)

Operating System: Fedora Linux 42
KDE Plasma Version: 6.3.80
KDE Frameworks Version: 6.15.0
Qt Version: 6.9.0
Kernel Version: 6.14.6-300.fc42.x86_64 (64-bit)
Graphics Platform: Wayland

Created attachment 181343 [details]
on 2nd screen

And, if you open the window on the laptop screen (Meta-ESC) it works.
Don't close the window, move it to the 4K screen: and it still works (context-menu is at mouse-pointer position)

But, if you initially start on 4K screen with (Meta-ESC), the context-menu still opens on the far right side

Could you please attach a screenshot of your screen arrangement? I cannot immediately reproduce with two screens.

Created attachment 181519 [details]
overview

Created attachment 181520 [details]
settings-laptop

Created attachment 181521 [details]
settings-4k

I have almost exactly the same screens and screen arrangement (the difference being a 23" 1440p external monitor rather than 27" 4K, but otherwise the same) and I can't reproduce the issue with the fix on my system.

how can i help any further?
even with latest updates (git), the problem is still there

Unclear. You're the only one who still seems to be able to reproduce the issue with the fix applied on with a multi-monitor setup, and we haven't found out what's different between your system and everyone else's

well, maybe one thing:
the 4K monitor is attached to a thunderbolt-4 box using usb-c ?
does this help?

Mine is plugged in via USB-C as well, though only to a USB-C+DP+PD port in the laptop, not a Thunderbolt port.

kscreen-doctor -o
Output: 1 eDP-1 e76f9ff2-7305-4bb4-bd07-e63d4dc45b41
        enabled
        connected
        priority 1
        Panel
        replication source:0
        Modes:  1:2880x1800@60*!  2:1920x1200@60  3:1920x1080@60  4:1600x1200@60  5:1680x1050@60  6:1280x1024@60  7:1440x900@60  8:1280x800@60  9:1280x720@60  10:1024x768@60  11:800x600@60  12:640x480@60  13:1600x1200@60  14:1280x1024@60  15:1024x768@60  16:2560x1600@60  17:1920x1200@60  18:1280x800@60  19:2880x1620@60  20:2560x1440@60  21:1920x1080@60  22:1600x900@60  23:1368x768@60  24:1280x720@60 
        Geometry: 0,0 2304x1440
        Scale: 1.25
        Rotation: 1
        Overscan: 0
        Vrr: incapable
        RgbRange: unknown
        HDR: disabled
        Wide Color Gamut: disabled
        ICC profile: none
        Color profile source: sRGB
        Color power preference: prefer efficiency and performance
        Brightness control: supported, set to 20% and dimming to 100%
        Color resolution: automatic (10), range: [8; 16] bits per color
        Allow EDR: always
Output: 2 DP-5 325a5680-6400-4830-b748-a193fd3a6cc4
        enabled
        connected
        priority 2
        DisplayPort
        replication source:0
        Modes:  25:3840x2160@60*!  26:3840x2160@30  27:1920x1200@60  28:1920x1080@60  29:1920x1080@60  30:1920x1080@60  31:1920x1080@50  32:1600x1200@60  33:1680x1050@60  34:1600x900@60  35:1280x1024@60  36:1440x900@60  37:1280x800@60  38:1280x720@60  39:1280x720@60  40:1280x720@60  41:1280x720@50  42:1024x768@60  43:800x600@60  44:720x576@50  45:720x576@50  46:720x480@60  47:720x480@60  48:720x480@60  49:720x480@60  50:640x480@60  51:640x480@60  52:640x480@60  53:720x400@70  54:1600x1200@60  55:1280x1024@60  56:1024x768@60  57:2560x1600@60  58:3200x1800@60  59:2880x1620@60  60:2560x1440@60  61:1920x1080@60  62:1600x900@60  63:1368x768@60  64:1280x720@60 
        Geometry: 2304,0 3840x2160
        Scale: 1
        Rotation: 1
        Overscan: 0
        Vrr: incapable
        RgbRange: unknown
        HDR: incapable
        Wide Color Gamut: incapable
        ICC profile: none
        Color profile source: sRGB
        Color power preference: prefer efficiency and performance
        Brightness control: unsupported
        Color resolution: automatic (10), range: [8; 16] bits per color
        Allow EDR: unsupported

all other context-menus are where they should be... (krusader, dolphin, others)

One more thing regarding system-monitor:
It's really only the right-click on the applications (or processes) list items.
If i click on the columns, the contextmenu is exactly at the mouse pointer position.
Even in applications, with details (sidebar on the right) enabled, right-clicking in the cpu/memory/network graphs shows the context menu spot on at the mouse-pointer.

Maybe one additional hint...as unlikely as it sounds: i'm using a left-handed mouse, so the buttons are swapped

Does it stop happening if you un-swap the buttons?

no, does not change anything if mouse is right/left handed

but, i got a coredump of systemsettings (before switching mouse handedness) ... preparing logs for attachment

Created attachment 181544 [details]
coredump1

Created attachment 181545 [details]
coredump2

the coredumps just happen after clicking (more than usual) in the various panels of systemmonitor.
No changes to the pages, just clicking on items, columns, switching pages and so forth

sorry... i meant systemmonitor (not systemsettings as in comment #28)

Created attachment 181667 [details]
In widget edit menu

I encountered something similar in the widget edit mode when I hove over "Delete widget" and such buttons. But instead of being shifted to the left, it's shifted to the right

The remaining issue that only affects the multi-screen use case has been fixed in Qt with https://codereview.qt-project.org/c/qt/qtbase/+/648321, thanks to Vlad Zahorodnii!

If that gets backported, it'll show up in a Qt 6.9.x release eventually too. Unclear right now whether this will happen.

*** Bug 505817 has been marked as a duplicate of this bug. ***