Multiple Window Interface for WPF

Multiple Document Interfaces (MDI) have come and gone in .NET and I am sure will someday come back again. In the meantime, I decided to write my very own implementation of MDI in WPF. Instead of multiple documents, I decided to extend my design to house multiple windows. The Multiple Window Interface contains many of the features of MDI with the addition of attachable windows. http://www.codeproject.com/KB/WPF/mwiwpf.aspx