With regards to prior art on server side decorations, there are some notable ones:
- KWin has a decoration API to allow decoration engines to exist for supporting different ways to theme them. An example of a consumer of this API is the first-party KDecoration engine. The first-party Aurorae decoration theme plugin uses this engine. The third-party Klassy theme also provides its own decoration theme plugin.
- LabWC implements the SSDs within itself, and allows customization through Openbox themes.
- Wayfire implements themed decorations as a plugin, and allows it to be swapped out. The third-party Firedecor plugin is an example alternative. The compositor can force SSDs to be drawn as a matter of configuration.
Most of the other ones out there are rather simple and not much more than what Mir does, but also there just are not that many dynamic and stacking Wayland compositors.