https://bugs.kde.org/show_bug.cgi?id=521386
Bug ID: 521386
Summary: Persistent black overlay (ghost window) on first
virtual desktop after enabling global window
transparency (kde-trans script or a window rule that
does the same)
Classification: Plasma
Product: kwin
Version First 6.6.5
Reported In:
Platform: Fedora RPMs
OS: Linux
Status: REPORTED
Severity: normal
Priority: NOR
Component: effects-various
Assignee: [email protected]
Reporter: [email protected]
Target Milestone: ---
Created attachment 193100
--> https://bugs.kde.org/attachment.cgi?id=193100&action=edit
This is a screenshot of the black ghost window/black desktop overlay.
Description
After enabling a global window transparency effect (using the kde-trans KWin
script or a similar rule that forces opacity on all windows), a black,
non-interactable overlay appears on the first virtual desktop only after every
login. This overlay behaves like a real window (it disappears when pressing
Meta+D to show the desktop, and reappears when restoring windows), but it
cannot be closed, moved, or interacted with. It can only be removed by
restarting kwin_wayland --replace. The issue does not occur if no global
transparency effect is active.
The overlay is not a normal window – it has no window class, no title, and
cannot be targeted by KWin window rules or KDE-Trans's own exclusion list. It
appears to be an artifact of KWin's compositor when forced opacity is applied
globally.
Steps to Reproduce
Install and enable a global transparency effect. For
Install the kde-trans KWin script (from KDE Store) or enable KDE-
Set windowOpacityPercentage=94 (or any value below
Ensure the script is enabled and
Log out of Plasma and log back
Observe the first virtual desktop (the one that is active immediately after
login). A black, rectangular overlay is present.
Press Meta+D (Show Desktop). The overlay disappears.
Press Meta+D again (restore windows). The overlay reappears.
Try to interact with it – it's impossible. There is no window title, no
close button, and it does not appear in task managers or window lists.
Run kwin_wayland --replace in a terminal. The overlay disappears and does
not return for the remainder of the session.
Observed Result
A persistent black rectangle (approx. full-screen size) covers the first
virtual desktop.
It behaves like a window (responds to Meta+D) but cannot be closed or
focused.
It does not appear on other virtual desktops unless the first desktop is
the active one at login.
The issue is 100% reproducible after every login when global transparency
is active.
Expected Result
No black overlay should appear. The global transparency effect should apply
cleanly to all normal application windows without creating compositor
artifacts.
What I Have Tried (and Did Not Work)
Disabling the Translucency desktop effect.
Excluding [kwin], [plasmashell], [kwin_wayland] in KDE-Trans's
excludedWindows field.
Using KWin window rules to force opacity of the overlay to 100% (failed
because the overlay has no identifiable window class).
Using qdbus org.kde.KWin /KWin supportInformation to find the overlay – it
does not appear in the window list.
Switching from KDE-Trans to the Klear script (same issue occurs).
Removing all tiling scripts (Krohnkite) – the issue persists as long as
global transparency is enabled.
The only workaround is to either:
Run kwin_wayland --replace after every login.
Additional Note
When I run "kwin" or "kwin_wayland" in terminal, I get a similar (the exact
same as the black overlay) window shown to me. I can close it, but I can't set
any special window or application setting for it, as it doesn't provide any
class name to the settings. It's title is "KDE Wayland Compositor WL-0"., and
when I run "sudo kwin", I get the same thing with the title "KDE Wayland
Compositor".
Also, the original overlay that appears on startup, can't be used with mouse at
all; it appears over desktop, and I can use desktop through it; I can't touch
the overlay, but the one that I open by with kwin command is intractable to
some extent.
Software / OS Versions
Operating System: Fedora Linux 43 (Workstation Edition)
KDE Plasma Version: 6.6.5
KDE Frameworks Version: 6.26.0
Qt Version: 6.8.3
Graphics Platform: Wayland
Graphics Hardware: Intel HD Graphics 520 (EliteBook 840 G3)
Windowing System: Wayland (X11 not affected – issue is Wayland‑specific)
Additional Information / Logs
Relevant logs from running kwin in a terminal (showing XKB errors and portal
registration failures):
text
No backend specified, automatically choosing Wayland because WAYLAND_DISPLAY is
set
unable to lock lockfile /run/user/1000/wayland-0.lock, maybe another compositor
is running
Accepting client connections on sockets: QList("wayland-1")
kf.globalaccel.kglobalacceld: Failed to register service org.kde.kglobalaccel
kwin_xkbcommon: XKB: [XKB-489] af:15:19: numeric keysym "0x100200d" (16785421)
... (full log attached separately)
qt.qpa.services: Failed to register with host portal
QDBusError("org.freedesktop.portal.Error.Failed", "Could not register app ID:
Unable to open /proc/44935/root")
qt.qpa.wayland: qtvirtualkeyboard currently is not supported at client-side,
use QT_IM_MODULES=qtvirtualkeyboard at compositor-side.
ShapeCorners: Writing Breeze config
Final Note:
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