For a given string path and SaveDocumentEventArgs e you can save the document depending on its file format: For FileFormat.RichTextFormat System.IO.File.WriteAllText(path, new System.Text.ASCIIEncoding().GetString(e.Document)) can be used and System.IO.File.WriteAllBytes(path, e.Document) for all other formats. The document's file format is specified in DocumentViewer.SaveDocumentEventArgs.FileFormat.
