constructor (index, item) {
    this.selected = false
    this.index = index
    this.item = item
    this.type = item.pathSegType

    this.ctrlpts = []
    this.ptgrip = null
    this.segsel = null
  }
@param {Integer} index
@param {SVGPathSeg} item
@todo Is `item` be more constrained here?