https://bugs.kde.org/show_bug.cgi?id=523823
Bug ID: 523823
Summary: Automatic Light/Dark theme not applied to desktop
shell at session start (apps get it, plasmashell
doesn't)
Classification: Plasma
Product: plasmashell
Version First 6.7.3
Reported In:
Platform: Fedora RPMs
OS: Linux
Status: REPORTED
Severity: normal
Priority: NOR
Component: general
Assignee: [email protected]
Reporter: [email protected]
CC: [email protected]
Target Milestone: 1.0
SUMMARY
When Plasma's automatic Light/Dark theme switching ("Auto" mode,
org.kde.NightTime-based) needs
to apply a scheme change that occurred while the machine was powered off (e.g.
overnight), the
desktop shell (plasmashell: panels, widgets, wallpaper) stays on the previous
session's theme,
while regular applications correctly display the new (correct) one. Manually
toggling the Global
Theme to a fixed value and back to "Auto" in System Settings fixes it instantly
for the rest of
the session — so the underlying computation is correct, only plasmashell's own
re-application at
login fails.
Note: the live switch (scheme change happening during an already-running
session, e.g. in the
evening) works correctly. The bug only affects the "catch-up" case at session
start.
This matches reports on KDE Discuss (no official bug number found there):
https://discuss.kde.org/t/kde-automatic-light-dark-mode-transition-broken/48813
STEPS TO REPRODUCE
1. Enable Global Theme > Auto (Light/Dark following day/night) in System
Settings.
2. Let the session cross a scheduled light/dark boundary while the machine is
fully powered off
(not just suspended) — e.g. shut down at night in dark mode, boot up the
next morning after
the scheduled switch-to-light time.
3. Observe plasmashell (panels, widgets, wallpaper) after login.
OBSERVED RESULT
plasmashell remains on the previous (incorrect) theme. Applications launched in
the same session
correctly show the new theme. kdeglobals' LookAndFeelPackage/ColorScheme values
are already correct
at this point — confirmed via `kreadconfig6 --file kdeglobals --group KDE --key
LookAndFeelPackage`.
Manually switching Global Theme away and back to "Auto" fixes plasmashell
immediately, with no
further intervention needed for the rest of the day.
EXPECTED RESULT
plasmashell should reflect the correct computed theme right after login,
without manual
intervention, matching what already happens for a live (mid-session) scheduled
switch.
SOFTWARE/OS VERSIONS
Fedora 44 (KDE Plasma, Wayland session)
plasma-workspace: 6.7.3-1.fc44 (plasma-workspace-6.7.3-1.fc44.x86_64)
kded6 module involved: lookandfeelautoswitcher
Related service: plasma-knighttimed.service (org.kde.NightTime)
ADDITIONAL INFORMATION
journalctl shows plasmashell.service, plasma-kded6.service (loads
lookandfeelautoswitcher) and
plasma-knighttimed.service all starting within the same second at login, with
no explicit
ordering dependency between them. Suspected cause: plasmashell relies on a push
notification
(DBus signal) from lookandfeelautoswitcher to react live, rather than pulling
the current
already-correct value once fully initialized — unlike regular
applications/portal consumers,
which pull fresh state at their own startup and are therefore immune to this
startup race.
Possibly related:
- Bug 511973 (transition timing, RESOLVED FIXED in 6.7.0)
- Bug 512139 (auto switch loses custom window decorations, ASSIGNED, MR !6064
in plasma-workspace)
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