This short article describes how to obtain the Xaml source code in an Extension for Expression Blend 4. It describes how to get read only access to the Xaml of for example MainPage.xaml, App.xaml, UserControl.xaml or ResourceDictionary.xaml from inside an extension for Expression Blend 4. It is built for use in Expression Blend 4 Silverlight 4 projects. With this as a starting point you can e.g. write your own Print-Xaml-Add-In or a BackUp-Xaml-Add-In for Microsoft Expression Blend 4.
The article is written in german language. You can use the Microsoft Translator Widget on my blog to translate the article in a language of your choice. The full source code of the sample Add-In project is provided.