如果设置navigator.series选项（如pointPlacement和pointPadding，pointWidth位于series.gantt中），则只会在导航器中显示里程碑。

navigator: {
    enabled: true,
    series: {
      type: 'gantt',
      pointPlacement: 0.5,
      pointPadding: 0.5,
    },
    yAxis: {
      min: 0,
      max: 4,
      reversed: true,
    }
  },
  series: [{
    name: 'Project 1',
    data: [{
      name: 'Create prototype',
      id: 'prototype',
      start: Date.UTC(2014, 10, 18),
      end: Date.UTC(2014, 10, 21)
    }, {
      name: 'Prototype done',
      dependency: 'prototype',
      start: Date.UTC(2014, 10, 21, 12),
      milestone: true,
      pointWidth: 10,
    }, {
      name: 'Develop',
      id: 'develop',
      start: Date.UTC(2014, 10, 20),
      end: Date.UTC(2014, 10, 25)
    }, {
      name: 'Development done',
      dependency: 'develop',
      start: Date.UTC(2014, 10, 25, 12),
      milestone: true,
      pointWidth: 10,
    }, {
      name: 'Test prototype',
      start: Date.UTC(2014, 10, 27),
      end: Date.UTC(2014, 10, 29)
    }, {
      name: 'Run acceptance tests',
      start: Date.UTC(2014, 10, 23),
      end: Date.UTC(2014, 10, 26)
    }]
  }]

演示：https://jsfiddle.net/BlackLabel/a94xkb0c/