anchor.diff:        _log.finest('DragEnd: deltaX=$deltaX');
         
         // Determine if we are past the threshold.
  -      if (deltaX.abs() > DISTANCE_THRESHOLD) {
  +      if (deltaX.abs() > distanceThreshold) {
           // Determine direction of swipe.
           bool directionRight = deltaX > 0;
           
  
positive.code:   /// CSS class set to the html body tag during a drag. Default is 
    /// 'swiper-drag-occurring'. If null, no CSS class is added.
    String dragOccurringClass = 'swiper-drag-occurring';
    
    // -------------------
    // Events
  
negative.code:  * A touch and mouse slider for swiping through images and html.
   */
  class Swiper {
    
    // -------------------
    // Options
    // -------------------
    /// How many pixels until a swipe is detected.
    int distanceThreshold = 20;
    
    /// CSS class set to the swiper element while a user is dragging. Default 
    /// class is 'swiper-dragging'. If null, no css class is added.
    String draggingClass = 'swiper-dragging';
  