setSelected (selected, isFirst) {
    this.selected = selected

    if (this.dom.tr) {
      if (selected) {
        addClassName(this.dom.tr, 'jsoneditor-selected')
      } else {
        removeClassName(this.dom.tr, 'jsoneditor-selected')
      }

      if (isFirst) {
        addClassName(this.dom.tr, 'jsoneditor-first')
      } else {
        removeClassName(this.dom.tr, 'jsoneditor-first')
      }

      if (this.append) {
        this.append.setSelected(selected)
      }

      if (this.showMore) {
        this.showMore.setSelected(selected)
      }

      if (this.childs) {
        this.childs.forEach(child => {
          child.setSelected(selected)
        })
      }
    }
  }
Select or deselect a node
@param {boolean} selected
@param {boolean} [isFirst]