/// <summary>
            /// Initializes a new instance of the Scroller class
            /// @pre control is not null
            /// </summary>
            /// <param name="control">The ExtendedScrollViewer to scroll</param>
            public Scroller(ExtendedScrollViewer control)
            {
                Debug.Assert(control != null, "control must not be null");
                _control = control;

                _timer.Elapsed += Timer_Elapsed;
            }
 /// <summary>
 /// Initializes a new instance of the Panner class
 /// @pre control is not null
 /// </summary>
 /// <param name="control">The ExtendedScrollViewer to scroll</param>
 public Panner(ExtendedScrollViewer control)
 {
     Debug.Assert(control != null, "control must not be null");
     _control = control;
 }