*Second in series after https://invent.kde.org/plasma/plasma-workspace-wallpapers/-/merge_requests/17*
Another patch will follow from the translations SVN, after I figure out how to work with it.
In kwin repo alone, there's another 4MB in savings with funny files like those:
```
kwin/po/ru/docs/kcontrol/windowspecific/tbird-reminder-info.png
[oxipng] Reduced by 768.94 KB (-96.42%) from 797.52 KB
```
The widget was renamed a while back, but the KCM still used the old
term to refer to it when letting the user choose the visual effect that
it shows the user. Let's change that.
BUG: 463087
FIXED-IN: 5.27
The Xrender backend was added at the time when OpenGL drivers were not
particularly stable. Nowadays though, it's a totally different situation.
The OpenGL render backend has been the default one for many years. It's
quite stable, and it allows implementing many advanced features that
other render backends don't.
Many features are not tested with it during the development cycle; the
only time when it is noticed is when changes in other parts of kwin break
the build in the xrender backend. Effectively, the xrender backend is
unmaintained nowadays.
Given that the xrender backend is effectively unmaintained and our focus
being shifted towards wayland, this change drops the xrender backend in
favor of the opengl backend.
Besides being de-facto unmaintained, another issue is that QtQuick does
not support and most likely will never support the Xrender API. This
poses a problem as we want thumbnail items to be natively integrated in
the qtquick scene graph.
Summary:
The "Candy" category suffers from some problems:
- It does not need to exist; everything in it is purely appearance-related and could live in the existing "Appearance" category
- The name is inappropriate; "Eye Candy" would be better, but changing it to this has proven controversial in the past
Let's just remove the category and move everything in it into the "Appearance" category.
Test Plan:
Apply and compile
Open Desktop Effects KCM
See that the "Candy" category is no more and the "Appearance" category has more stuff in it
Reviewers: #kwin, #vdg, zzag, abetts
Reviewed By: #kwin, #vdg, zzag, abetts
Subscribers: abetts, zzag, kwin, kde-doc-english, GB_2
Tags: #kwin, #documentation
Differential Revision: https://phabricator.kde.org/D27658
