code: function(evt) {
          var passes = true;
          if (this.pixelTolerance != null && this.down && this.down.xy) {
              passes = this.pixelTolerance >= this.down.xy.distanceTo(evt.xy);
              // for touch environments, we also enforce that all touches
              // start and end within the given tolerance to be considered a click
              if (passes && this.touch && 
                  this.down.touches.length === this.last.touches.length) {
                  // the touchend event doesn't come with touches, so we check
                  // down and last
                  for (var i=0, ii=this.down.touches.length; i<ii; ++i) {
                      if (this.getTouchDistance(
                              this.down.touches[i], 
                              this.last.touches[i]
                          ) > this.pixelTolerance) {
                          passes = false;
                          break;
                      }
                  }
              }
          }
          return passes;
      }
docs: Method: passesTolerance
  Determine whether the event is within the optional pixel tolerance.  Note
  that the pixel tolerance check only works if mousedown events get to
  the listeners registered here.  If they are stopped by other elements,
  the <pixelTolerance> will have no effect here (this method will always
  return true).
  
  Returns:
  {Boolean} The click is within the pixel tolerance (if specified).