I posted a question a few months ago about sharing resource dictionaries across assemblies. It turns out you can do that using the Component Resource Key markup extension. At the time, I could only get it working with a WPF Custom Control project, not with a plain Class Library project.

Now I need to use an existing plain Class Library project to host a shared resource dictionary. That means I need to retrofit the Class Library project to support the Component Resource Key markup extension. I have added a Themes folder and a Generic.xaml resource dictionary document to the Class Library project, as well as references to PresentationCore, PresentationFramework, and WindowsBase. Unfortunately, that doesn't seem to do the trick.

So, here is my question: Other than the above, what does a WPF Custom Control Library project have that a plain Class Library project doesn't? Or, to put it another way, what else could I add to my class library project to get this feature working? Thanks.