unhighlight () {
    if (this.locked) {
      return
    }

    const me = this
    if (this.node) {
      this._cancelUnhighlight()

      // do the unhighlighting after a small delay, to prevent re-highlighting
      // the same node when moving from the drag-icon to the contextmenu-icon
      // or vice versa.
      this.unhighlightTimer = setTimeout(() => {
        me.node.setHighlight(false)
        me.node = undefined
        me.unhighlightTimer = undefined
      }, 0)
    }
  }
Unhighlight currently highlighted node.
Will be done after a delay