Bug 460805

Summary:	With Blend Changes effect active, there's temporary image ghosting with wallpapers and accent colors when wallpaper changes automatically
Product:	[Plasma] kwin	Reporter:	tobiasturi
Component:	effects-various	Assignee:	KWin default assignee <kwin-bugs-null>
Status:	REPORTED ---
Severity:	minor	CC:	kde, nate
Priority:	NOR
Version First Reported In:	5.26.1
Target Milestone:	---
Platform:	Arch Linux
OS:	Linux
Latest Commit:		Version Fixed/Implemented In:
Sentry Crash Report:

Description tobiasturi 2022-10-21 13:46:26 UTC

SUMMARY
Under specific circumstances wallpapers with accent colours can cause temporary ghosting of the last displayed image on screen and sometimes freeze applications visually altogether when they are focused or unfocused requiring them to be relaunched. This does not show up in software based recorders.
***

STEPS TO REPRODUCE
1. set wallpaper to slide show of wallpapers
2. set accent colour to change will wallpaper
3. play a moving image and wait for the background to change (or if you're lucky it will happen to any rendered window ie. obs, firefox, chrome, unity, EU4, etc.)

OBSERVED RESULT
1.The screen ghosts the last displayed image for a few seconds
and/or
2.An application becomes permanently locked in the last displayed few frames requiring to be relaunched

EXPECTED RESULT
Wallpaper changes with accent colours should not freeze the screen or visually lock up applications.

SOFTWARE/OS VERSIONS
KDE Frameworks Version: 5.99.0
Qt Version: 5.15.6

ADDITIONAL INFORMATION
Kernel Version: 6.0.2-1-ck (64-bit) (persists on other official kernels ie. LTS)
Graphics Platform: X11
Processors: 4 × Intel® Core™ i5-6600K CPU @ 3.50GHz
Memory: 46.0 GiB of RAM
Graphics Processor: AMD Radeon RX 580 Series
Manufacturer: MSI
Product Name: MS-7998
System Version: 1.0

Comment 1 Nate Graham 2022-10-21 17:19:09 UTC

Weird interaction with Blend effect, maybe? Does it go away if you disable the "Blend Changes" effect in System Settings > Workspace Behavior > Desktop Effects? To see it on that page, you will have to click on the little filter button next to the search field and uncheck "Exclude internal effects."

Also, does the issue reproduce in a Wayland session?

Comment 2 tobiasturi 2022-10-21 18:41:59 UTC

(In reply to Nate Graham from comment #1)
> Weird interaction with Blend effect, maybe? Does it go away if you disable
> the "Blend Changes" effect in System Settings > Workspace Behavior > Desktop
> Effects? To see it on that page, you will have to click on the little filter
> button next to the search field and uncheck "Exclude internal effects."
> 
> Also, does the issue reproduce in a Wayland session?

Disabling blend effects stops the ghosting both in X11 and wayland.

The ghosting exists with effect blending on in both X11 and wayland

Comment 3 Nate Graham 2022-10-21 18:44:12 UTC

It does seem like a bug in the Blend Changes effect, then. Can't reproduce it myself with an Intel iGPU. Might be an issue related to your graphics drivers.

Comment 4 tobiasturi 2022-10-21 19:05:51 UTC

(In reply to Nate Graham from comment #3)
> It does seem like a bug in the Blend Changes effect, then. Can't reproduce
> it myself with an Intel iGPU. Might be an issue related to your graphics
> drivers.

I'm just using mesa. I tried mesa-git in the AUR and had the same issue.