COSMIC is a desktop environment specially created for the Pop!_OS distribution by the veteran Linux PC manufacturer System76. It is written in Rust and uses the native Rust cross-platform graphics toolkit Iced.

Iced is a cross-platform GUI library written for the Rust programming language “with a focus on simplicity and type safety”. Iced’s design philosophy is inspired by the Elm language. The Iced toolkit is not only available for Linux, macOS and Windows, but also for web applications.

COSMIC is not a product built from the ground up, but is based on the GNOME desktop environment, which System76 hopes to provide a complete and polished desktop user experience in Pop!_OS. The biggest difference between the two, and also the biggest highlight of COSMIC, is customization. System76 sees this as an elegant solution, envisioning customization to make the desktop easier to use, a powerful and productive feature for users.

According to reports, System76 will continue to actively develop COSMIC this year, such as the ongoingdynamic rendering. System76 Principal Engineer Jeremy wrote iced-dyrend, a dynamic renderer for COSMIC DE. He also added software rendering to iced-dyrend through his development work on the latest version of Softbuffer. This dynamic renderer has been integrated into the Iced toolkit.

Additionally, the COSMIC desktop environment uses the Wayland display server, a program that communicates with the rest of the system to run the application, display it on the screen, and register user input. But Wayland is relatively new compared to X11 display servers, so some applications may not be compatible.

In this scenario, XWayland plays a role. The XWayland display server includes a compatibility layer for applications running on Wayland using X11. Currently System76 engineer Victoria has integrated XWayland into the cosmic-comp synthesizer, and the engineering team has been testing how X11 applications such as Firefox and Steam run on the COSMIC desktop environment.

See the announcement for more details.