Vertical line markers
I would like to add vertical line markers to mark for events which happened during the time-series data (like device reboot). Like flags from Highstock, just without any label associated and line going from top to bottom. With axis flags it is hard to precisely see when the event occurred when having multiple series plotted. And because the event is for multiple series all together, it is not reasonable to put them onto a particular series.
What you are describing is plot lines, see http://api.highcharts.com/highcharts#xAxis.plotLines
I want same "Vertical line markers" but with tooltip to show devices actions time.