Most of the window decorations available for KWin are not native decorations but themes for a native theme engine, such as deKorator, Smaragd, QtCurve or my own Aurorae. Themes are much easier to design and to distribute than a native decoration which has to be implemented in C++ and be distributed by the Linux distribution. Thus themes are an important part of the decoration system.
But we did a very bad job of integrating the themes into our configuration system. The configuration system only knows about native decorations and doesn’t know that the native decoration is in fact a theme engine. This makes selecting a theme difficult, because a user has to first select the theme engine and then configure this to select the theme. Downloading new themes through GHNS is also difficult as again it requires to go through the configuration of the theme engine. We can do better.
I started working on that port back in the last KDE Telepathy sprint in Barcelona last April. Back then, I started to work on it because I have been doing heavy usage of the KTp plasmoids back when using the KDE 4 Plasma series and I didn’t want to live without them. Back then, I only ported the minimum parts of ktp-common-internals so it would work with KF5, as well as the plasmoids. It was quite some work, but definitely worth it since I’ve been using them ever since, and it’s worked wonderfully.
When the first CSD “what if” was made in the KDE community forums it became the catalyst that got me in touch with some of the fine developers who really do make KDE happen, from them and members of the VDG I was educated on a new method of decorating windows with clean yet powerful widgets, and I have the privilege of presenting the idea we have worked and iterated on for some weeks now today...
KDE contributor and graphics designer Ken Vermette has penned an interesting series of KDE "What if..." articles where he talks about (and has some visual mock-ups) about what KDE might look like with client-side decorations along and separately if KDE were to use Windows 10 design components.
The main technical challenges faced by KDE developers is ensuring application consistency will continue to work under various form-factors. When Kwin (the KDE window manager) controls window borders, it can quickly and gracefully adapt to multiple form-factors. For example, in Plasma active space is at such a premium KDE can hide window decorations and embed them into the workspace itself.
The other technical challenge is protocol and cross-enviornment consistency. It’s known that CSD-enabled applications can look extremly awkward when window borders are wrapped around an application not designed to use them. In addition, protocols for drawing CSDs on Linux are a mish-mash at best, and CSD code tends to be far less portable to other desktop environments. Compounding that, KDE has additional features (such as window tabbing) which are inherently incompatible with the feature.
ZevenOS-Neptune 4.x branch is called "It's all about you" and it was initially made available back in June. This is the second update for the distribution and the devs have refined some of the features and have added some new packages into the mix.
The system is based on KDE, but don't expect to find a regular stock version implemented. It's clear that the devs have put a lot of effort into making the DE experiences unique. Users can immediately recognize what distribution they are looking at just with a glance, and that's always a good sign.