The document box is a widget that contains a document. The document can be obtained through the Document property. To set the content of the document you can use the Content property of the document box. It is a shortcut property to the document. If you set the InheritStyleSheetsProperty of the document box's document to false, then the widgets hosted in it will not inherit the styling of the document the document box is placed in, which is useful if you want to create a set of content whose styling is independent of the styling of the application. You can even apply a completely different theme to the document box's document:

documentBox.Document.InheritStyleSheets = false;
documentBox.Document.StyleSheets.ApplyTheme(new NMacLionTheme());