Recently, Microsoft introducing the open-source UWP Community Toolkit, a new project that enables the developer community to collaborate and contribute new capabilities on top of the SDK. The UWP Community Toolkit is a collection of helper functions, custom controls, and app services. It simplifies and demonstrates common developer tasks building UWP apps for Windows 10.
UWP Community Toolkit Sample App
If you want to see the toolkit in action before jumping into the code, Microsoft also released UWP Toolkit Sample App.
In the future, Microsoft plan to release stable updates through the Visual Studio NuGet package at a regular cadence.
The toolkit is completely open-sourced on GitHub, including the source code of the toolkit, source code of the sample app and even the documentation. The roadmap for the next release is available here.