Edit 05/05/2020 : after upgrading the problem was diminished, making Plasma usable again. More information in this answer below viewtopic.php?f=111&t=163966#p431866

Hi,

I am running Debian testing with several desktop : i3, awesome and Plasma.

About 3 weeks ago, I started having heavy display issues when using Plasma

Description of the issue : (sorry about the fuzziness)

* The image is jumping, especially the taskbar blink all the time, when I press the main menu, the menu bar also blink (being more hidden than displayed actually).
* I managed to open a terminal, but then any change in the interface becomes a black square. For example if I begin to type, the current line will become black, if I hover the mouse over menu they will become black boxes. In this situation going to another tty and back reset the interface (black squares disappear)
* In overall the interface is not usable

I can't really say what specific action triggered this behavior, as I don't use Plasma so often. I think after updating the packages using

Code: Select all

sudo apt update && sudo apt upgrade

.

I don't see any problem using others window managers.

Creating a new user doesn't solve the problem.

Versions are :

Operating System: Debian GNU/Linux
KDE Plasma Version: 5.14.5
Qt Version: 5.12.5
KDE Frameworks Version: 5.62.0
Kernel Version: 5.3.0-3-amd64
OS Type: 64-bit
Processors: 4 × Intel® Core™ i3-3217U CPU @ 1.80GHz
Memory
Graphic card: 3.7 GiB of RAM

Graphic card
Intel Corporation 3rd Gen Core processor Graphics Controller

Please excuse me for the little information I'm providing. I will be glad to answer your questions.

Your Plasma version is not exactly very recent, so rather hard to debug.

Which exact Plasma theme do you use? Did you change anything from the default settings?

Hi, thank you for your interest.

I use Breeze dark, even though changing the theme doesn't change the behavior.

I don't remember changing any display setting appart from changing to dark theme.

Please tell me any useful information I could provide. I am not a Plasma or KDE expert so I don't know what is needed to understand an issue.

Hi,

I had this same type of thing happening with KDE Plasma 5.17 on Kubuntu 19.10. It was small things at first, then it got to about what he's describing. Ultimately, I was forced to reinstall, and chose to wipe, and go with Kubuntu 18.04LTS, as I couldn't get it straight.

I was also using Breeze Dark, and never tested with other themes.

It got so bad that every time I'd click anything anywhere, open a window, or type in any window, the UI would flash black, and it'd either stay that way, or it would fix itself, and give a message that kwin crashed. I know it's not much to go on, but I hope it helps get the issue fixed, even if just a little bit.

That is weird, I use Breeze Dark myself since a while and haven't seen this at all. Could be graphic card related, though.
I have a rather old laptop with an Intel card, too: Intel Corporation Skylake GT2 [HD Graphics 520] (rev 07)

Thank you for sharing, I'm glad to see I'm not alone.

This is my full graphical configuration

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matthias@matthias-pc:~$ lspci -vnn | grep VGA -A 12
00:02.0 VGA compatible controller [0300]: Intel Corporation 3rd Gen Core processor Graphics Controller [8086:0166] (rev 09) (prog-if 00 [VGA controller])
        Subsystem: Acer Incorporated [ALI] 3rd Gen Core processor Graphics Controller [1025:0835]
        Flags: bus master, fast devsel, latency 0, IRQ 28
        Memory at c0000000 (64-bit, non-prefetchable) [size=4M]
        Memory at b0000000 (64-bit, prefetchable) [size=256M]
        I/O ports at 2000 [size=64]
        [virtual] Expansion ROM at 000c0000 [disabled] [size=128K]
        Capabilities: <access denied>
        Kernel driver in use: i915
        Kernel modules: i915

00:14.0 USB controller [0c03]: Intel Corporation 7 Series/C210 Series Chipset Family USB xHCI Host Controller [8086:1e31] (rev 04) (prog-if 30 [XHCI])
        Subsystem: Acer Incorporated [ALI] 7 Series/C210 Series Chipset Family USB xHCI Host Controller [1025:0835]


Any idea how to troubleshoot this ?
Maybe a video would help ?

This issue was solved doing last updates of debian testing.

I still get glitches on login and when having pop-ups.

To get an idea, this is a look of the screen I originaly had
https://postimg.cc/Q9Xy5x0W

How is your screen connected, built-in or is it an external one? If it is an external one through HDMI, check your cable, as these tend to be quite tricky at times. A DVI connection is usually better, less hassle with the cable and also a better transmission for high resolution.

Hi,
Thank you for your answer.

It does feel like it is not connected correctly, but I'm using the builtin screen of my laptop, and there is no problem when using another windows manager (i3 or awesome-wm), or when using Windows 10, so I'm ruling out hardware issues.

I found related threads on the internet :

• https://www.youtube.com/watch?v=d_zVI_yY6r0 show very similar issue
  
• I tried disabling PSR (I have Intel 3rd generation builtin graphic card)
  https://wiki.archlinux.org/index.php/in ... flickering
  
• This thread suggest editing composer settings
  https://askubuntu.com/questions/672007/ ... plasma-5-4

None of these solutions worked.

In the new version the OS is much more usable than when I recorded the video. There is only some small flickering from time to time, for example on the task bar, on notifications, or when I lock the screen on start to type my password to login. It is very visible on the login screen, image is flickering when switching from the locked screen when only the clock to the blurred lock screen with the input password form on the foreground.

New version are :

Operating System: Debian GNU/Linux
KDE Plasma Version: 5.17.5
KDE Frameworks Version: 5.62.0
Qt Version: 5.12.5
Kernel Version: 5.5.0-2-amd64
OS Type: 64-bit
Processors: 4 × Intel® Core™ i3-3217U CPU @ 1.80GHz
Memory: 3.7 GiB of RAM

I am a bit at loss here, but it has to do with the graphics stack. I move this thread to the KWin section of the forum.