selectAdditionalOnPoint(pointer) {
    let selectionChanged = false;
    if (this.options.selectable === true) {
      const obj = this.getNodeAt(pointer) || this.getEdgeAt(pointer);

      if (obj !== undefined) {
        selectionChanged = true;
        if (obj.isSelected() === true) {
          this.deselectObject(obj);
        } else {
          this.selectObject(obj);
        }

        this.body.emitter.emit("_requestRedraw");
      }
    }
    return selectionChanged;
  }
@param {{x: number, y: number}} pointer
@returns {boolean}