code: function (xy) {
          var startX = this.dragHandler.start.x;
          var startY = this.dragHandler.start.y;
          var deltaX = Math.abs(startX - xy.x);
          var deltaY = Math.abs(startY - xy.y);
  
          var offset = this.getBoxOffsets();
          this.zoomBox.style.width = (deltaX + offset.width + 1) + "px";
          this.zoomBox.style.height = (deltaY + offset.height + 1) + "px";
          this.zoomBox.style.left = (xy.x < startX ?
              startX - deltaX - offset.left : startX - offset.left) + "px";
          this.zoomBox.style.top = (xy.y < startY ?
              startY - deltaY - offset.top : startY - offset.top) + "px";
      }
docs: Method: moveBox