Bug 461782

Something somewhat similar but not quite identical happened a few minutes ago.

The task manager stopped responding completely to mouse events.
Unlike in the initial report, not only would it not respond to left clicks, but also right clicks and mouse-over (icons wouldn't "shine" when moving the mouse cursor over).

There was also a notification baloon on the bottom right of the screen which (A) contained garbage, (B) wouldn't vanish and (C) did not have any window borders or close button. Leftovers were visible of the notification it initially contained, from Thunderbird, but it was all mangled.

Applications were initially functioning properly. I could switch between them with Alt+Tab.
The Shift+Super+D shortcut to minimize all windows was not working though.

Then after a while things got worse. I was using Gimp (in order to edit a screenshot that I intended to attach to this report). Then I opened a tool in Gimp, one of those that open in a separate small window, and at that instant, Gimp's  main window disappeared, or minimized, or went to the background, anway was no longer visible (but the small window with the tool was). 
Now alt+Tab no longer worked either.

Additionally, when I opened a virtual terminal with Ctrl+Alt+F2, it was responding sluggishly to keyboard.
At this point I had to hard-reset with the laptop's On/Off button.

Until recently, I was suffering from this:
https://forum.manjaro.org/t/entire-system-randomly-becomes-unstable-windows-flicker-and-sometimes-stop-responding/125241

I never reported that bug to KDE because I always assumed it belonged to something else at a much lower level (kernel, CPU drivers or something like that). I've been recently told in another thread that that is "definitely not" a kernel bug and that it is certainly in KDE. I don't know.
Anyway, a reply to that thread suggested that I try adding the parameter ahci.mobile_lpm_policy=1 to my kernel configuration in Grup, and so I did.
Since then, instead of the symptoms described in that report, I have started experiencing the issues described in this one.
That may be a coincidence, they could be two separate unrelated issues, but it's suspicious.

The exact same as in my last comment happened again. Well just the first part up to and not including "then after a while things got worse".

I did ctrl+Alt+f2, from there I killed plasmashell, then back to Ctrl+Alt+F1, and from a terminal I restarted plasmashell with "kstart5 plasmashell". This restored normal behavior without having to reboot (but note that I wasn't able to do the same in other cases).

Why plasmashell isn't restarted automatically when it crashes or is killed, is beyond me.

Now that I see that restarting plasmashell restores normal behavior, I'm wondering if the issue is actually in plasmashell, and whether it is a variation of #447717 (although with somewhat different symptoms).

*** I NEED URGENT HELP ***

This has happened to me many more times and now once again I am in this situation again. 

I have Kate and Gimp open with TONS of unsaved work.
I can't manage to give them focus so that I can save my work before rebooting.
If I reboot now I'll lose a lot of unsaved, unrecoverable valuable work.

All I need is a workaround to give focus to an application while the windows manager or whatever is unresponsive.

I have been able to grab a Chrome tab to get here and write this, because the portion of Chrome with the tabs was luckily visible, but nether Kate nor Gimp are at the moment, and Alt+Tab doesn't work

Alt+F2 to show KRunner, then restart KWin by typing `kwin_x11 --replace`?

> Alt+F2 to show KRunner, then restart KWin by typing `kwin_x11 --replace`?

Wow thank you! This saved my life, and now I have a workaround for when this crap happens (which is about once a day), so I can resume working without losing all my unsaved work and having to reboot.

Is this related to #447717?

> I am already on Plasma 5.26.4.

Actually, I installed a bunch of updates a few hours ago and haven't rebooted since. 

So I don't know if MAYBE it could be the case that:
- before the updates I was running a previous version of Plasma
- now Plasma 5.26.4 has been installed and shows up in "About this system"
- but I'm still running 5.26.4 (or I was when it crashed crash) since I didn't reboot after installing the upgrade.

Either that, or the workaround isn't working.

> I don't think so, since that bug [447717] only affects Wayland.

Does it though?
I reported 461600 and it got marked as duplicate of 447717. The symptoms in that occasion matched pretty well what's described in 447717.


P.S my previous comment and your reply got incorrectly marked as spam

This happened to me twice a few hours apart.

The second time, after I relaunched kwin with the workaround in comment 6, it crashed again and again after a few seconds like 3 or 4 times. Then plasmashell also crashed, and I relaunched with "kstart5 plasmashell" from a terminal

I believe I'm experiencing the same issue: after a while kwin crashes (window decorations disappear) and one has to restart it (`kwin_x11 --replace`); then it repeats again.

After the crash, there are these messages in the terminal:

```
kwin_core: XCB error: 3 (BadWindow), sequence: 41305, resource id: 144759611, major code: 129 (SHAPE), minor code: 6 (Input)
qt.qpa.xcb: QXcbConnection: XCB error: 3 (BadWindow), sequence: 41306, resource id: 144759611, major code: 2 (ChangeWindowAttributes), minor code: 0
The X11 connection broke: I/O error (code 1)
X connection to :0 broken (explicit kill or server shutdown).
file:///usr/share/kwin/outline/plasma/outline.qml:14: TypeError: Cannot read property 'longDuration' of null
```

The XCB errors are numerous, but the X11 connection error appears only at the end.

Am experiencing this in Ubuntu 22.10 (X11 session), which includes
- KDE Plasma Version: 5.26.4
- KDE Frameworks Version: 5.100.0
- Qt Version: 5.15.6
- Kernel Version: 5.19.0-26-generic (64-bit)

KWin reports my system as:
OpenGL vendor string:                   Intel
OpenGL renderer string:                 Mesa Intel(R) Xe Graphics (TGL GT2)
OpenGL version string:                  4.6 (Compatibility Profile) Mesa 22.2.1
OpenGL shading language version string: 4.60
Driver:                                             Intel
GPU class:                                      Tiger Lake
OpenGL version:                           4.6
GLSL version:                                 4.60
Mesa version:                                 22.2.1
X server version:                            1.21.1
Linux kernel version:                     5.19
Requires strict binding:                 yes
GLSL shaders:                                 yes
Texture NPOT support:                  yes
Virtual Machine:                             no

Hope this helps to isolate and solve the issue...