Any alternative for IsSubclassOf or IsAssignableFrom in C# Metro-style

Many of the reflection methods can be found in the System.Reflection.TypeInfo class.

You can get an instance of TypeInfo for your Type using the GetTypeInfo extension method, provided by System.Reflection.IntrospectionExtensions:

using System.Reflection;

// ...

ui.GetType().GetTypeInfo().IsSubclassOf(type)