CoW: a stacking window manager for Wayland, built on River

CoW (Compositor on Wayland) is a stacking window manager published on Codeberg that uses the existing River compositor underneath. The code is written in C, and the latest release, 0.3, came out in September 2026.

What CoW is

A stacking model means windows float over one another and the user decides where each one sits and how large it is. CoW follows the lineage of FVWM and MWM: the project set out to reproduce the 90s look and feel of those window managers while still allowing more modern styles.

A 90s desktop in a tiling era

On Wayland, window managers mostly follow the tiling principle: windows split the screen automatically and stop covering each other. CoW is an explicit choice against that model, so it manages position and size through individual commands instead of a strict grid.

Its headline features include server-side decorations that can be customised, native menus, window placement commands and iconified windows. A single desktop can hold a container, a pager, menus and launcher buttons.

Scriptability: IPC and an internal DSL

CoW is configured directly through commands, and the same commands work in its configuration file, which makes the manager scriptable from external applications. On top of that come IPC scripting, rules that control scripting, and an internal DSL for filtering.

0.4 and the community

The next release, 0.4, already counts 21 merged changes. According to the development changelog, modules are moving from threads to event loops, and the release adds an alias command, named window selections and an anchored window placement mode.

The project has a small but friendly community. IRC is the main channel, at #cow-wayland on irc.libera.chat. Issues are reported over IRC or through Codeberg, and there is a wiki open to contributions.