/// <summary>
 /// Scroll the ScrollViewer right by a page.
 ///
 /// </summary>
 /// <param name="viewer">The ScrollViewer.</param><exception cref="T:System.ArgumentNullException"><paramref name="viewer"/> is null.
 ///             </exception>
 public static void PageRight(this ScrollViewer viewer)
 {
     if (viewer == null)
     {
         throw new ArgumentNullException("viewer");
     }
     ScrollViewerExtensions.ScrollByHorizontalOffset(viewer, viewer.ViewportWidth);
 }
 /// <summary>
 /// Scroll the ScrollViewer right by a line.
 ///
 /// </summary>
 /// <param name="viewer">The ScrollViewer.</param><exception cref="T:System.ArgumentNullException"><paramref name="viewer"/> is null.
 ///             </exception>
 public static void LineRight(this ScrollViewer viewer)
 {
     if (viewer == null)
     {
         throw new ArgumentNullException("viewer");
     }
     ScrollViewerExtensions.ScrollByHorizontalOffset(viewer, 16.0);
 }