MSDN has released a new article which shows how to implement a Word-like UI object model architecture that supports automation etc. like Office does.
The object model demonstrated is based on the model-view-controller (MVC) design pattern.
All Microsoft Office applications are built on top of an object model that supports automation. Any developer can use the 0bject model to drive the application UI and add, edit, and delete content, just as a real user interacts with the application. The rich object model, together with automation support, makes Office applications truly extensible and pluggable. Anyone can write a powerful add-in within a very short time in order to extend the behavior of Microsoft Word according to their own need. As good object-oriented (OO) developers, we develop our applications with rich architecture and with a reasonably good object model following the Model-View-Controller (MVC) design pattern.
However, until recently, very few applications have been developed that offer automation similar to Microsoft Office applications. As a result, we cannot extend our applications the same way we can extend and customize Office applications using the .NET Framework and Microsoft Visual Basic for Applications (VBA). This article shows you a way to implement a Microsoft Word-like object model for your own .NET application. We will be following the Model-View-Controller design pattern and also .NET Framework events and delegates heavily. The object model we will develop here will add infinite extensibility to our application. It will give us the opportunity to add plug-in and scripting capability to our applications as designed, without writing additional code for them. The plug-in and scripting feature will have the same power as the core application. The design will also produce a very clean code base that truly decouples business logic from the UI logic. Best of all, we will be able to write code to drive the UI and thus create test scripts that not only test business logic but also test the UI behaviors.
Read Implement a Microsoft Word-like Object Model for Your .NET Framework Application on MSDN.