Implementing a C# text editor in a separate WPF application

I am adding an interactive C# component to an existing WPF application. I feel (fairly) confident in the backend work: I know how to programmatically use the Scripting APIs to evaluate the code, etc. But I don't know WPF at all and don't know how to just get a text window that will give me the hooks to do things like Intellisense (e.g., a callback that is executed whenever the user types a "."). I would love to start with a simple example if someone can point me to it.

Thanks!

Mike

Mike Barnett