WinRT XAML does not support behaviors out of the box. This library tries to fill the gap for people who really need behaviors to get cracking in XAML for Windows 8 apps.
Version 1.0.2 adds a bit of Blend support
Install-Package WinRtBehaviors -Version 1.0.2
dotnet add package WinRtBehaviors --version 1.0.2
This package has no dependencies.