Canonical released Mir 2.30 on September 24. Mir is not a desktop you install directly. It is a library for building Wayland compositors, handling graphics and input hardware and offering sensible window management defaults so a shell author does not have to. Ubuntu Frame, the Lomiri phone and tablet shell, and Miracle WM are all built on it.

What is new

wl_fixes protocol support. wl_fixes is a small core Wayland protocol that exists to correct mistakes in the original protocol design without breaking old clients, such as providing a way to destroy objects that the base protocol forgot to give a destructor. Supporting it keeps Mir-based compositors compatible with toolkits that start relying on it.

Rust is now mandatory at build time. Mir 2.30 packages a new Rust-based evdev input platform, the layer that reads keyboards, mice, and touchpads from the kernel. Input handling parses a constant stream of device events, which is exactly the kind of code where memory safety pays off. It follows the direction Canonical has taken elsewhere, including Rust coreutils in Ubuntu and sudo-rs.

Also new:

• A typed wrapper for wl_array, improving type safety in Mir’s own protocol code
• libxml++ 5.0 support, with a fallback for older distributions

Fixes

• Horizontal scroll speed can now be configured
• Cursor roles are set correctly on hidden surfaces
• Multi-display GBM/KMS setups work properly
• Output resizing is handled correctly
• Unmanaged surfaces are handled safely, and role conflicts are reported properly

ABI

mirserver bumps to ABI 69. miral stays at 8, mircommon at 13, and mircore at 3, so most compositors built on the stable MirAL API only need a rebuild, not code changes.

Install it from your distribution rather than building from source, particularly now that the build needs a Rust toolchain. If you want to understand what a compositor actually does, our Wayland vs X11 explainer is the place to start.