dist/vue-draggable-nested-tree.es.js
function offsetToViewPort() {
      var r = this.nodeInnerEl.getBoundingClientRect();
      r.x = r.left;
      r.y = r.top;
      return r;
    }
function offsetToViewPort() {
      var r = this.nodeInnerEl.getBoundingClientRect();
      r.x = r.left;
      r.y = r.top;
      return r;
    }
right bottom point