Microsoft's Phased Open-Sourcing of WinUI: A Six-Month Roadmap

Microsoft announced a phased approach to open-sourcing WinUI, the user interface framework for Windows 11. Due to WinUI's complexity and deep integration with Windows, open-sourcing won't be a simple switch flip. Microsoft plans a four-phase rollout: Phase 1 increases GitHub mirroring frequency; Phase 2 allows external developers to build locally; Phase 3 enables external contributions and testing; and Phase 4 establishes GitHub as the primary development platform. This will be an incremental process, and Microsoft encourages developer feedback and contributions.