Created attachment 121666 [details]
When settings scale effects on closing windows, it generates visual artifacts on the area that is not being actively refreshed, until those areas gets the focus.
STEPS TO REPRODUCE
1. Open system settings
2. Go to Desktop Behavior
3. Select Desktop Effects
4. Activate Scale animation setting the close scale more than 1x
5. Open multiple windows (not fullscreen) so that once you close one, there is at least one inactive window in background.
A flickering visual artifact appears (It may last for long time)
Clean closing animation
Linux/KDE Plasma: Kubuntu 19.04
(available in About System)
KDE Plasma Version: 5.16.3
KDE Frameworks Version: 5.59.0
Qt Version: 5.12.2
This bug is pretty easy to verify. It happens with both the desktop with an AMD card and a notebook that uses Nvidia proprietary driver.
Created attachment 121667 [details]
Video showing the artifacts
> It happens with both the desktop with an AMD card
Hmm, I'm not able to reproduce this bug. What's your animation speed?
Created attachment 122383 [details]
The speed is just sightly faster than standard
Created attachment 122384 [details]
Window animation duration 150ms
As to how to reproduce it, it is important that when the window scales on close, it scales to more than 1x (I have 1.2), then it happens basically every time. There are almost always artifacts. Sometimes they flicker in reaction to mouse movement, sometimes they stand still.
About the composition, sometimes a whole portion of window remains there (like the upper bar, with the buttons to minimize, maximize, ... sometimes ii's just the shadow of the window that remains there.
If you haven't seen the video yet, please look at it.
Alright, after tweaking animation speed I reproduced the bug but only once. It's very difficult bug to reproduce.
Created attachment 143124 [details]
Scale Up Effect Visual Bug Demonstration
Happened upon this bug recently when changing the settings of the Scale effect.
Can't get the bug to show when closing, but when opening windows it's quite noticeable.
This happens when the "scale" setting is over 1,00.