After reading your question I decided to start working on a new version of that tutorial.
A few things to get you started right away.
I've created the basic plugin like this:
using System.ComponentModel.Composition;
using Microsoft.Expression.Extensibility;
namespace Demo.Extension
{
[Export(typeof (IPackage))]
public class Demo : IPackage
{
public void Load(IServices services)
{
}
public void Unload()
{
}
}
}
Make sure you:
- place the plugins in ...\Blend Preview\extensions
- run visual studio as administrator to be able to deploy to that folder during debug
- implement the IPackage instead of IPlugin