https://bugs.kde.org/show_bug.cgi?id=511186
Bug ID: 511186
Summary: Phantom base key input after Ctrl shortcuts when
switching windows (Wayland only)
Classification: Plasma
Product: kwin
Version First 6.4.0
Reported In:
Platform: Fedora RPMs
OS: Linux
Status: REPORTED
Severity: major
Priority: NOR
Component: wayland-generic
Assignee: [email protected]
Reporter: [email protected]
Target Milestone: ---
**Summary:**
After pressing a Ctrl-based shortcut (e.g., Ctrl+C, Ctrl+V, Ctrl+S) in any
application under Fedora KDE Plasma Wayland, if I switch focus to another
window and click to place the caret, a **single phantom character**
corresponding to the shortcut’s base key (`c`, `v`, `s`) is immediately
inserted.
- It's not continuous (like `ccccccccccc`), it's just one; so I believe this is
not related to sticky keys or key repeat.
- This occurs **whenever I switch windows and click on the editor**, after
performing a Ctrl-based shortcut, whether immediately or after a few seconds.
- Happens only on Wayland, and **does not occur under X11** or on Windows, so
it is **not a keyboard hardware issue**.
- Any text already selected in the target window is replaced by the phantom
character.
- This started happening as soon as I migrated from Windows 11 to Fedora 42, a
few months ago, using the same hardware. I've been updating the system since,
but the issue is still happening.
**Steps to reproduce:**
1. Open any application (e.g., Firefox or Chrome) and select some text.
2. Press Ctrl+C to copy, and release.
3. Switch to a text editor (e.g., VSCode, Kate, LibreOffice Writer) by either:
3.1. `Alt + Tab`
3.2. Click to place the caret.
4. Observe that a `c` (or corresponding base key) is inserted automatically at
the caret, even though no key was pressed.
If using `Alt + Tab`, and text was already selected previously, that text will
be replaced by the `c` character.
**Expected behavior:**
Only the shortcut action should occur; no base key event should be sent to the
new window.
**Actual behavior:**
A single phantom key corresponding to the shortcut’s base key is inserted at
the caret.
**Frequency:**
Sporadic, but reproducible several times a day, when switching after Ctrl
shortcuts.
**System info:**
Fixed PC, with a keyboard, a mouse, 2 screens.
Operating System: Fedora Linux 42
KDE Plasma Version: 6.4.5
KDE Frameworks Version: 6.19.0
Qt Version: 6.9.2
Kernel Version: 6.17.4-200.fc42.x86_64 (64-bit)
Graphics Platform: Wayland
Processors: 6 × Intel® Core™ i5-8400 CPU @ 2.80GHz
Memory: 32 GiB of RAM (31.3 GiB usable)
**Possible cause:**
Wayland/KWin appears to **fail to suppress the base key after a modifier
release during window focus change**, leading to a phantom key being delivered
to the newly focused window.
**Possibly related issue:**
In some applications (especially LibreOffice Writer, rarely VS Code), after a
Ctrl-based shortcut and window switch, the caret can become a **dotted bar that
follows the mouse**, scrolling the document as the mouse moves.
This behavior appears connected to the phantom key issue, likely caused by the
same delayed or misinterpreted modifier/focus events in Wayland/KWin.
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