[kwin] [Bug 371480] New: SDL2 Apps causing desktop effects to disappear, task-manager function weirdly, all desktop widgets to disappear and sometimes kwin to crash

[Martin Chang via KDE Bugzilla]

https://bugs.kde.org/show_bug.cgi?id=371480

Bug ID: 371480
Summary: SDL2 Apps causing desktop effects to disappear,
task-manager function weirdly, all desktop widgets to
disappear and sometimes kwin to crash
Product: kwin
Version: 5.7.5
Platform: unspecified
OS: Linux
Status: UNCONFIRMED
Severity: normal
Priority: NOR
Component: general
Assignee: kwin-bugs-***@kde.org
Reporter: ***@gmail.com

While I'm working on my Ray Tracer I found that causes the entire desktop to
lose all the effects, task-manager function weirdly (missing some opened
window), all desktop widgets to disappear and sometimes kwin to crash.
Everything will comeback to normal after closing the SDL2 window.
After more testing, I found that its SDL2 causing it. Even running simple SDL2
tutorial codes will resulting in the situation described above.
Note that I seems to only happen with SDL2. Creating and running SDL1 windows
does not cause the problem.

My ray tracer: https://bitbucket.org/Seanstone5923/simpleray
SDL2 tutorial code that I found that can reproduce the issue:
http://lazyfoo.net/tutorials/SDL/02_getting_an_image_on_the_screen/index.php

Reproducible: Always

Steps to Reproduce:
1. Compile and run any SDL2 program (LazyFoo's tutoral or my Ray Tracer will do
the job)
2. Weird things described above starts to happen

Actual Results:
Weird things described above starts to happen

Expected Results:
Work properly.

- Happens on both Intel and Nvidia GPU(proprietary driver, not tested on
Mesa), not tested on AMD GPUs.
- No matter what composting back-end I'm using. It will happen.
- Tested with SDL 2.0.4

[Martin Gräßlin via KDE Bugzilla]

https://bugs.kde.org/show_bug.cgi?id=371480

Martin Gräßlin <***@kde.org> changed:

What |Removed |Added
----------------------------------------------------------------------------
Status|UNCONFIRMED |RESOLVED
Resolution|--- |WORKSFORME

--- Comment #1 from Martin Gräßlin <***@kde.org> ---
This is expected behavior. SDL sets a hint to disable the compositor for better
performance and KWin honors this. With Plasma 5.8 we introduced a GUI config
option where you can disable this behavior in general.

With Plasma 5.7 you can already create a window specific rule to disallow
"Block Compositing". Create a rule for the window and select "Force" "No". That
will ensure that the compositing does not get disabled.