https://bugs.kde.org/show_bug.cgi?id=507507
Bug ID: 507507
Summary: Qt 6.10 causes Qt application windows to appear at
0,0/top-left ignoring KWin rules.
Classification: Plasma
Product: kwin
Version First 6.3.5
Reported In:
Platform: Other
OS: Linux
Status: REPORTED
Severity: normal
Priority: NOR
Component: general
Assignee: [email protected]
Reporter: [email protected]
Target Milestone: ---
SUMMARY
After going from Qt 6.9 to 6.10 back in June 2025, I noticed that the KWin
'Window Behaviour' / 'Window placement' setting seems to be completely ignored
for Qt applications, and new windows will open at 0,0, or in other words,
top-left of the left-most screen on a three-screen set-up running X11.
Perhaps likely a Qt bug, or at least changed behaviour, but filing here first
for visibility and such until I get to look deeper into the matter myself.
STEPS TO REPRODUCE
1. Run KWin X11 on LXQt in a three-display set-up (probably should see this on
full Plasma, and single-display set-up too).
2. Set 'Window placement' to anything other than 'top-left corner'.
3. Make sure 'Allow apps to remember the psoitions of their own windows, if
they support it' is disabled.
4. Run a Qt application, something like 'kcalc' for example, and observe it
being placed at 0,0, or top-left corner instead of, for example, randomly or
centred.
OBSERVED RESULT
New Qt application windows always appear at 0,0, or top-left corner, if they
don't remember their last position.
EXPECTED RESULT
Windows are placed according to the KWin 'Window placement' setting.
SOFTWARE/OS VERSIONS
Linux/KDE Plasma: Gentoo Linux (Not a full Plasma install, but using KWin with
LXQt.)
KDE Plasma Version: 6.4.3
KDE Frameworks Version: 6.16.0
Qt Version: 6.10 (838d543cd2adddce6419faa91647192653d71088)
ADDITIONAL INFORMATION
Wayland behaviour not tested at all.
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