title: WPF Printing FlowDocument not centering
body: <p>I want to print a page from some text I have with a small header. 
  I wanted all the text to be centered on the page but I'm not sure how to do it.. </p>
  
  <p>Here is my code..   t is of type track which is just an object that holds information like artist name, album name, song title, and lyrics. </p>
  
  <pre><code> PrintDialog dialog = new PrintDialog();
              if (dialog.ShowDialog() != true)
              { return; }
              FlowDocument doc = new FlowDocument();
              Section sec = new Section();
              Paragraph header = new Paragraph();
              Paragraph body = new Paragraph();
              Bold boldSong = new Bold();
              boldSong.Inlines.Add(new Run(t.Song));
              header.Inlines.Add(boldSong);
              header.Inlines.Add(new LineBreak());
              Bold boldArtist = new Bold();
              if (!string.IsNullOrWhiteSpace(t.Artist))
              {
                  boldArtist.Inlines.Add(new Run(t.Artist));
                  header.Inlines.Add(boldArtist);
                  header.Inlines.Add(new LineBreak());
              }
              Bold boldAlbum = new Bold();
              if (!string.IsNullOrWhiteSpace(t.Album))
              {
                  boldAlbum.Inlines.Add(new Run(t.Album));
                  header.Inlines.Add(boldAlbum);
                  header.Inlines.Add(new LineBreak());
              }
              header.TextAlignment = TextAlignment.Center;
              body.Inlines.Add(t.iTunesFileTrack.Lyrics);
              body.TextAlignment = TextAlignment.Center;
              doc.Blocks.Add(header);
              doc.Blocks.Add(body);
              doc.Name = "FlowDoc";
              IDocumentPaginatorSource idpSource = doc;
              DocumentPaginator holder = idpSource.DocumentPaginator;
              holder.PageSize = new Size(dialog.PrintableAreaWidth,
          dialog.PrintableAreaHeight);
              dialog.PrintDocument(holder, "Lyrics");
  </code></pre>
  
  <p>The page prints just fine except for the fact that the whole thing clings to the left of the document when printed... I know there is some property I'm not setting correctly or not setting at all.. </p>