• WPF Persistence Specification
• The WpfDesign library is meant to contain only the basic designer extensibility framework and interfaces for use by designer extensions.
• All public types and methods in the WpfDesign library should be documented with xml comments.
• WpfDesign.Designer contains the designer implementation: the main DesignSurface, the service implementations, and designer extensions for the built-in WPF controls
• WpfDesign.XamlDom is a document object model that contains a XmlDocument and the object instances created from it. XamlDom contains a custom XAML parser.
• WpfDesign doesn't use XAML directly: The abstract DesignItem class in WpfDesign allows plugging in a custom backend.

WPF Designer Tasks (rather old post from Daniel)