Trying to add an image to a RichTextBox progamatically from a Stream. The image displays in the text box, however when reading the Xaml property there is no markup for the image.

    private void richTextBox3_Drop(object sender, DragEventArgs e)
    {
        if (e.Data.GetDataPresent(DataFormats.FileDrop))
        {
            FileInfo[] files = (FileInfo[])e.Data.GetData(DataFormats.FileDrop);
            using (Stream s = files[0].OpenRead())
            {
                InlineUIContainer container = new InlineUIContainer();
                BitmapImage bmp = new BitmapImage();
                bmp.SetSource(s);
                Image img = new Image();
                img.SetValue(Image.SourceProperty, bmp);
                container.Child = img;

                richTextBox3.Selection.Insert(container);
            }
        }
    }

    private void Button_Click_1(object sender, RoutedEventArgs e)
    {
        // this doesn't have the markup from the inserted image
        System.Windows.MessageBox.Show(richTextBox3.Xaml);
    }

What is the correct way to insert an image into the RichTextBox at runtime so that it can be persisted to a data store? In the Xaml property.