First Floor Software is moving its open source projects to GitHub. Modern UI for WPF (MUI) is the latest project that is now available on GitHub.
MUI is an open source project for WPF containing a set of controls and styles converting your WPF application into a great looking Modern UI app. MUI is a spin-off of XAML Spy.
Another open source project XAML Conditional Compilation (XCC) has been moved from codeplex to Github a couple of days ago.