function enable () {
  buttons = [
    {
      tooltip: 'Previous Track',
      icon: PREV_ICON,
      click: () => windows.main.dispatch('previousTrack')
    },
    {
      tooltip: 'Pause',
      icon: PAUSE_ICON,
      click: () => windows.main.dispatch('playPause')
    },
    {
      tooltip: 'Next Track',
      icon: NEXT_ICON,
      click: () => windows.main.dispatch('nextTrack')
    }
  ]
  update()
}
Show the Windows thumbnail toolbar buttons.