Bug 504536 - Fit-content panel sometimes does not shrink in width when an Icons-only task manager icon icon is removed
Summary: Fit-content panel sometimes does not shrink in width when an Icons-only task ...
Status: RESOLVED UPSTREAM
Alias: None
Product: plasmashell
Classification: Plasma
Component: Task Manager and Icons-Only Task Manager widgets (other bugs)
Version First Reported In: 6.3.90
Platform: Fedora RPMs Linux
: NOR normal
Target Milestone: 1.0
Assignee: Plasma Bugs List
URL:
Keywords:
Depends on:
Blocks:
 
Reported: 2025-05-19 17:16 UTC by altmail
Modified: 2025-05-30 14:02 UTC (History)
6 users (show)

See Also:
Latest Commit:
Version Fixed/Implemented In:
Sentry Crash Report:


Attachments
Video demonstrating the issue (169.50 KB, video/mp4)
2025-05-19 17:16 UTC, altmail
Details
Some of the files from the .config directory for my Plasma configuration. (6.38 KB, application/zip)
2025-05-28 00:29 UTC, altmail
Details

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Description altmail 2025-05-19 17:16:54 UTC
Created attachment 181530 [details]
Video demonstrating the issue

SUMMARY
When closing an application results in an icon disappearing from a floating and centered Icons-only task manager, the panel sometimes does not properly update its size and appearance until hovering over it with the mouse cursor.


STEPS TO REPRODUCE
1. Create an icons-only task manager panel; make it floating and centered and variable-width.
2. Open an application that creates a new icon on the task manager.
3. Close the application.

OBSERVED RESULT
The icon is gone, but the task manager keeps its previous width and the remaining icons appear to be slightly squished, leaving empty space where the icon was previously displayed.

EXPECTED RESULT
The task manager changes its size accordingly and does not leave empty space behind.

SOFTWARE/OS VERSIONS
Linux/KDE Plasma: Fedora Linux 42
KDE Plasma Version: 6.3.90 (from the @kdesig/kde-beta copr)
KDE Frameworks Version: 6.14.0
Qt Version: 6.9.0

ADDITIONAL INFORMATION
Kernel Version: 6.14.6-300.fc42.x86_64 (64-bit)
Graphics Platform: Wayland
Processors: 12 × AMD Ryzen 5 5600X 6-Core Processor
Memory: 16 GiB of RAM (15.5 GiB usable)
Graphics Processor: NVIDIA GeForce RTX 2070 (using the proprietary nvidia driver version 575.51.02)
Comment 1 Nate Graham 2025-05-19 18:37:59 UTC
From your screen recording (thanks, it was very helpful!) it looks like the background gets updated properly, but the mask or blur area or something lags behind.

I can't seem to make it happen when I replicate your setup, though.
Comment 2 Akseli Lahtinen 2025-05-20 12:18:45 UTC
Can you list all the widgets you have in this panel? Do you have any padding/separator items?
Comment 3 altmail 2025-05-20 13:44:03 UTC
The panel only contains (from left to right) an application launcher, a margin separator and the icons-only task manager.

Interestingly, it seems like this is an issue only with the proprietary NVIDIA driver - I can't reproduce it with nouveau.
Comment 4 Lenzoid 2025-05-20 18:01:35 UTC
Also seems to work as expected here, latest git master with Nvidia Beta drivers. Like many other bugs in current nvidia "stable" driver it might have already been fixed.
Comment 5 altmail 2025-05-21 00:09:30 UTC
(In reply to Lenzoid from comment #4)
> Also seems to work as expected here, latest git master with Nvidia Beta
> drivers. Like many other bugs in current nvidia "stable" driver it might
> have already been fixed.

As mentioned in the report, I was also using the beta version (575.51.02) of the NVIDIA driver. I've since tried to downgrade to the release version to see if it would change anything (which it didn't). Unless there is a newer beta version than 575.51.02 (which is the newest one listed on https://www.nvidia.com/en-us/drivers/unix/), it does still seem to be a problem.
Comment 6 altmail 2025-05-28 00:27:12 UTC
I'm not sure if this helps, but I've experimented a bit by renaming the old `plasma-org.kde.plasma.desktop-appletsrc` and `plasmashellrc` files in the .config directory to get a default state for the panels and then modifying just the default panel to look like the one in the report. The issue doesn't seem to occur until I clone that panel my second screen. Sadly, I wasn't yet able to reproduce the issue on a separate Fedora 42 install with the same Plasma version and NVIDIA driver...
Comment 7 altmail 2025-05-28 00:29:31 UTC
Created attachment 181805 [details]
Some of the files from the .config directory for my Plasma configuration.
Comment 8 altmail 2025-05-28 00:46:04 UTC
Sorry for the spamming, but I've just discovered that I AM actually able to reproduce it on the separate Fedora installation. The reason I wasn't able to before was because the NVIDIA driver wasn't properly loading due to secure boot being enabled, which meant the installation was actually using the nouveau driver.
Comment 9 Niccolò Venerandi 2025-05-28 11:14:54 UTC
Isn't this an upstream driver issue, if it only occurs with one specific driver?
Comment 10 altmail 2025-05-28 16:28:47 UTC
I thought the issue was closed because it was concluded that it had already been fixed in the beta version of the NVIDIA driver (which it hasn't for me), which is why I reopened it and added some information. I totally understand that it's probably not very motivating to hear of yet another NVIDIA-only issue though, so I'll close it again if you don't want to investigate further.
Comment 11 Lenzoid 2025-05-28 16:55:51 UTC
Bollocks... I can repro this! Will try on my AMD system and add more information shortly (I don't think its driver or gpu related)
Comment 12 Lenzoid 2025-05-30 12:56:07 UTC
With Nvidia card it's easily reproducible: Here's the complete repro video including the setup of the task bar: https://youtu.be/w9xYHZaxup4 It's basically what OP has written in video format. It is on stable 570.153.02 drivers.

- Reproducible on Nvidia drivers 570.153.02 (stable) and 575.51.02-2 (beta), aswell as 575.57.08-1 (beta). 
- One difference I found: It seems that on stable drivers it appears every single time, while on beta drivers only every 2-4 times you close a window.
- Not reproducible on my AMD system.

Since it's not driver version specific I'll reopen. If this is truly an upstream issue, could you please provide information on what to report this as or link a Nvidia ticket? I don't know how I would describe this in a potential issue tbh.

However I don't see any other visual glitches like that, is it possible plasmashell draws it in a different way so so that this glitch doesn't occur in the first place?
Comment 13 Nate Graham 2025-05-30 14:02:12 UTC
Yeah, based on that information, it's clearly a driver issue.

Please report this issue to the NVIDIA folks, either by sending an email to linux-bugs@nvidia.com or making a post at https://forums.developer.nvidia.com/c/gpu-graphics/linux. It would be helpful to the NVIDIA developers if you could run nvidia-bug-report.sh and attach the resulting file in your report.

Thanks!