Bug 513607

Summary: Alternating between TAB and ` while holding ALT wreaks havoc
Product: [Plasma] kwin Reporter: Travis <info>
Component: wayland-genericAssignee: KWin default assignee <kwin-bugs-null>
Status: CONFIRMED ---    
Severity: crash CC: nate
Priority: NOR    
Version First Reported In: unspecified   
Target Milestone: ---   
Platform: Debian stable   
OS: Linux   
Latest Commit: Version Fixed/Implemented In:
Sentry Crash Report:

Description Travis 2025-12-20 13:36:45 UTC
Alternating between TAB and ` while holding ALT causes unusual window behaviour if more than one program is running.  Doing so with more than two programs running causes KDE system crash.

STEPS TO REPRODUCE
1. Open more than one program (ex. System Monitor and Firefox)
2. Press Alt+Tab
3. Without releasing Alt, hit the ` key

OBSERVED RESULT

erratic behavior and or crash of KDE

EXPECTED RESULT

I was expecting window switching mode to change from "all windows" mode to "only windows of a single program" mode.

SOFTWARE/OS VERSIONS
Debian12
Linux/KDE Plasma: 
KDE Plasma Version: 5.27.5
KDE Frameworks Version: 5.103.0
Qt Version: 5.15.8

ADDITIONAL INFORMATION

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           PID: 1541 (kwin_wayland)
           UID: 1000 (orchid)
           GID: 1000 (orchid)
        Signal: 11 (SEGV)
     Timestamp: Sat 2025-12-20 06:34:11 CST (59min ago)
  Command Line: /usr/bin/kwin_wayland --wayland-fd 7 --socket wayland-0 --xwayland-fd 8 --xwayland-fd 9 --xwayland-display :1 --xwayland-xauthority /run/user/1000/xauth_QBnHoh --xwayland
    Executable: /usr/bin/kwin_wayland
 Control Group: /user.slice/user-1000.slice/user@1000.service/session.slice/plasma-kwin_wayland.service
          Unit: user@1000.service
     User Unit: plasma-kwin_wayland.service
         Slice: user-1000.slice
     Owner UID: 1000 (orchid)
       Boot ID: 50cf356773ae40a5b4c1e26f31300e91
    Machine ID: 7fdce6e2536a4c2289c39751e3f54976
      Hostname: orchid-inspiron3521
       Storage: /var/lib/systemd/coredump/core.kwin_wayland.1000.50cf356773ae40a5b4c1e26f31300e91.1541.1766234051000000.zst (inaccessible)
       Message: Process 1541 (kwin_wayland) of user 1000 dumped core.
                
                Module libsystemd.so.0 from deb systemd-252.39-1~deb12u1.amd64
                Module libudev.so.1 from deb systemd-252.39-1~deb12u1.amd64
                Stack trace of thread 1541:
                #0  0x00007fe1a6f7ecd0 _ZNK14QOpenGLContext7surfaceEv (libQt5Gui.so.5 + 0x17ecd0)
                #1  0x00007fe1a7dedfdf n/a (libQt5Quick.so.5 + 0x1edfdf)
                #2  0x00007fe1a7dea6b2 n/a (libQt5Quick.so.5 + 0x1ea6b2)
                #3  0x00007fe1a7e869d0 _ZN14QQuickTextNode9addGlyphsERK7QPointFRK9QGlyphRunRK6QColorN10QQuickText9TextStyleES8_P7QSGNode (libQt5Quick.so.5 + 0x2869d0)
                #4  0x00007fe1a7e8bcf8 n/a (libQt5Quick.so.5 + 0x28bcf8)
                #5  0x00007fe1a7e879e8 _ZN14QQuickTextNode13addTextLayoutERK7QPointFP11QTextLayoutRK6QColorN10QQuickText9TextStyleES7_S7_S7_S7_iiii (libQt5Quick.so.5 + 0x2879e8)
                #6  0x00007fe1a7e864b1 _ZN10QQuickText15updatePaintNodeEP7QSGNodePN10QQuickItem19UpdatePaintNodeDataE (libQt5Quick.so.5 + 0x2864b1)
                #7  0x00007fe1a7e66bc8 _ZN19QQuickWindowPrivate15updateDirtyNodeEP10QQuickItem (libQt5Quick.so.5 + 0x266bc8)
                #8  0x00007fe1a7e670eb _ZN19QQuickWindowPrivate16updateDirtyNodesEv (libQt5Quick.so.5 + 0x2670eb)
                #9  0x00007fe1a7e68c3d _ZN19QQuickWindowPrivate14syncSceneGraphEv (libQt5Quick.so.5 + 0x268c3d)
                #10 0x00007fe1a7de62e7 n/a (libQt5Quick.so.5 + 0x1e62e7)
                #11 0x00007fe1a7e76e20 _ZN12QQuickWindow5eventEP6QEvent (libQt5Quick.so.5 + 0x276e20)
                #12 0x00007fe1a6162fae _ZN19QApplicationPrivate13notify_helperEP7QObjectP6QEvent (libQt5Widgets.so.5 + 0x162fae)
                #13 0x00007fe1a6ab1738 _ZN16QCoreApplication15notifyInternal2EP7QObjectP6QEvent (libQt5Core.so.5 + 0x2b1738)
                #14 0x00007fe1a6f2c4f3 _ZN15QPlatformWindow11windowEventEP6QEvent (libQt5Gui.so.5 + 0x12c4f3)
                #15 0x00007fe1a616a1f9 _ZN12QApplication6notifyEP7QObjectP6QEvent (libQt5Widgets.so.5 + 0x16a1f9)
                #16 0x00007fe1a6ab1738 _ZN16QCoreApplication15notifyInternal2EP7QObjectP6QEvent (libQt5Core.so.5 + 0x2b1738)
                #17 0x00007fe1a6b08c71 _ZN14QTimerInfoList14activateTimersEv (libQt5Core.so.5 + 0x308c71)
                #18 0x00007fe1a6b071f0 _ZN20QEventDispatcherUNIX13processEventsE6QFlagsIN10QEventLoop17ProcessEventsFlagEE (libQt5Core.so.5 + 0x3071f0)
                #19 0x0000563226c1596d n/a (kwin_wayland + 0x14996d)
                #20 0x00007fe1a6ab01bb _ZN10QEventLoop4execE6QFlagsINS_17ProcessEventsFlagEE (libQt5Core.so.5 + 0x2b01bb)
                #21 0x00007fe1a6ab8316 _ZN16QCoreApplication4execEv (libQt5Core.so.5 + 0x2b8316)
                #22 0x0000563226b20f28 n/a (kwin_wayland + 0x54f28)
                #23 0x00007fe1a5a4524a n/a (libc.so.6 + 0x2724a)
                #24 0x00007fe1a5a45305 __libc_start_main (libc.so.6 + 0x27305)
                #25 0x0000563226b22ee1 n/a (kwin_wayland + 0x56ee1)
                
                Stack trace of thread 1557:
                #0  0x00007fe1a5b1a25f __poll (libc.so.6 + 0xfc25f)
                #1  0x00007fe1a431e90e n/a (libglib-2.0.so.0 + 0x5490e)
                #2  0x00007fe1a431ea2c g_main_context_iteration (libglib-2.0.so.0 + 0x54a2c)
                #3  0x00007fe1a6b09876 _ZN20QEventDispatcherGlib13processEventsE6QFlagsIN10QEventLoop17ProcessEventsFlagEE (libQt5Core.so.5 + 0x309876)
                #4  0x00007fe1a6ab01bb _ZN10QEventLoop4execE6QFlagsINS_17ProcessEventsFlagEE (libQt5Core.so.5 + 0x2b01bb)
                #5  0x00007fe1a68cabc7 _ZN7QThread4execEv (libQt5Core.so.5 + 0xcabc7)
                #6  0x00007fe1a68cbd83 n/a (libQt5Core.so.5 + 0xcbd83)
                #7  0x00007fe1a5aa71f5 n/a (libc.so.6 + 0x891f5)
                #8  0x00007fe1a5b278dc n/a (libc.so.6 + 0x1098dc)
                
                Stack trace of thread 1558:
                #0  0x00007fe1a5aa3f16 n/a (libc.so.6 + 0x85f16)
                #1  0x00007fe1a5aa65d8 pthread_cond_wait (libc.so.6 + 0x885d8)
                #2  0x00007fe19e10c059 n/a (crocus_dri.so + 0x10c059)
                #3  0x00007fe19e0be17b n/a (crocus_dri.so + 0xbe17b)
                #4  0x00007fe19e10bf97 n/a (crocus_dri.so + 0x10bf97)
                #5  0x00007fe1a5aa71f5 n/a (libc.so.6 + 0x891f5)
                #6  0x00007fe1a5b278dc n/a (libc.so.6 + 0x1098dc)
                
                Stack trace of thread 1556:
                #0  0x00007fe1a5aa3f16 n/a (libc.so.6 + 0x85f16)
                #1  0x00007fe1a5aa65d8 pthread_cond_wait (libc.so.6 + 0x885d8)
                #2  0x00007fe19e10c059 n/a (crocus_dri.so + 0x10c059)
                #3  0x00007fe19e0be17b n/a (crocus_dri.so + 0xbe17b)
                #4  0x00007fe19e10bf97 n/a (crocus_dri.so + 0x10bf97)
                #5  0x00007fe1a5aa71f5 n/a (libc.so.6 + 0x891f5)
                #6  0x00007fe1a5b278dc n/a (libc.so.6 + 0x1098dc)
                
                Stack trace of thread 5769:
                #0  0x00007fe1a5aa3f16 n/a (libc.so.6 + 0x85f16)
                #1  0x00007fe1a5aa65d8 pthread_cond_wait (libc.so.6 + 0x885d8)
                #2  0x00007fe19e10c059 n/a (crocus_dri.so + 0x10c059)
                #3  0x00007fe19e0be17b n/a (crocus_dri.so + 0xbe17b)
                #4  0x00007fe19e10bf97 n/a (crocus_dri.so + 0x10bf97)
                #5  0x00007fe1a5aa71f5 n/a (libc.so.6 + 0x891f5)
                #6  0x00007fe1a5b278dc n/a (libc.so.6 + 0x1098dc)
                
                Stack trace of thread 1554:
                #0  0x00007fe1a5b1a25f __poll (libc.so.6 + 0xfc25f)
                #1  0x00007fe1a431e90e n/a (libglib-2.0.so.0 + 0x5490e)
                #2  0x00007fe1a431ea2c g_main_context_iteration (libglib-2.0.so.0 + 0x54a2c)
                #3  0x00007fe1a6b09876 _ZN20QEventDispatcherGlib13processEventsE6QFlagsIN10QEventLoop17ProcessEventsFlagEE (libQt5Core.so.5 + 0x309876)
                #4  0x00007fe1a6ab01bb _ZN10QEventLoop4execE6QFlagsINS_17ProcessEventsFlagEE (libQt5Core.so.5 + 0x2b01bb)
                #5  0x00007fe1a68cabc7 _ZN7QThread4execEv (libQt5Core.so.5 + 0xcabc7)
                #6  0x00007fe1a8ab7487 n/a (libQt5DBus.so.5 + 0x17487)
                #7  0x00007fe1a68cbd83 n/a (libQt5Core.so.5 + 0xcbd83)
                #8  0x00007fe1a5aa71f5 n/a (libc.so.6 + 0x891f5)
                #9  0x00007fe1a5b278dc n/a (libc.so.6 + 0x1098dc)
                
                Stack trace of thread 1561:
                #0  0x00007fe1a5b1a25f __poll (libc.so.6 + 0xfc25f)
                #1  0x00007fe1a431e90e n/a (libglib-2.0.so.0 + 0x5490e)
                #2  0x00007fe1a431ea2c g_main_context_iteration (libglib-2.0.so.0 + 0x54a2c)
                #3  0x00007fe1a6b09876 _ZN20QEventDispatcherGlib13processEventsE6QFlagsIN10QEventLoop17ProcessEventsFlagEE (libQt5Core.so.5 + 0x309876)
                #4  0x00007fe1a6ab01bb _ZN10QEventLoop4execE6QFlagsINS_17ProcessEventsFlagEE (libQt5Core.so.5 + 0x2b01bb)
                #5  0x00007fe1a68cabc7 _ZN7QThread4execEv (libQt5Core.so.5 + 0xcabc7)
                #6  0x00007fe1a7928555 n/a (libQt5Qml.so.5 + 0x328555)
                #7  0x00007fe1a68cbd83 n/a (libQt5Core.so.5 + 0xcbd83)
                #8  0x00007fe1a5aa71f5 n/a (libc.so.6 + 0x891f5)
                #9  0x00007fe1a5b278dc n/a (libc.so.6 + 0x1098dc)
                
                Stack trace of thread 1559:
                #0  0x00007fe1a5aa3f16 n/a (libc.so.6 + 0x85f16)
                #1  0x00007fe1a5aa65d8 pthread_cond_wait (libc.so.6 + 0x885d8)
                #2  0x00007fe19e10c059 n/a (crocus_dri.so + 0x10c059)
                #3  0x00007fe19e0be17b n/a (crocus_dri.so + 0xbe17b)
                #4  0x00007fe19e10bf97 n/a (crocus_dri.so + 0x10bf97)
                #5  0x00007fe1a5aa71f5 n/a (libc.so.6 + 0x891f5)
                #6  0x00007fe1a5b278dc n/a (libc.so.6 + 0x1098dc)
                
                Stack trace of thread 8693:
                #0  0x00007fe1a5b1a25f __poll (libc.so.6 + 0xfc25f)
                #1  0x00007fe1a431e90e n/a (libglib-2.0.so.0 + 0x5490e)
                #2  0x00007fe1a431ea2c g_main_context_iteration (libglib-2.0.so.0 + 0x54a2c)
                #3  0x00007fe1a6b09876 _ZN20QEventDispatcherGlib13processEventsE6QFlagsIN10QEventLoop17ProcessEventsFlagEE (libQt5Core.so.5 + 0x309876)
                #4  0x00007fe1a6ab01bb _ZN10QEventLoop4execE6QFlagsINS_17ProcessEventsFlagEE (libQt5Core.so.5 + 0x2b01bb)
                #5  0x00007fe1a68cabc7 _ZN7QThread4execEv (libQt5Core.so.5 + 0xcabc7)
                #6  0x00007fe1a7928555 n/a (libQt5Qml.so.5 + 0x328555)
                #7  0x00007fe1a68cbd83 n/a (libQt5Core.so.5 + 0xcbd83)
                #8  0x00007fe1a5aa71f5 n/a (libc.so.6 + 0x891f5)
                #9  0x00007fe1a5b278dc n/a (libc.so.6 + 0x1098dc)
                ELF object binary architecture: AMD x86-64
Comment 1 Nate Graham 2025-12-22 17:55:05 UTC
I can't reproduce the crash, but doing this does have some weird effects.