Vaadin dchart highlighter get cursor value

Hi,
i’m using a vaadin dchart:
https://vaadin.com/directory#!addon/dcharts-widget
My chart is pretty much like this demo chart:
http://vaadin.dussan.org/dchartsdemo/#lineCharts/highlightingCursorAndTrendline
My problem is, in this demo chart the .setTooltipFormatString(“hello %.2f”)
is only showing the Y Axis value. I need the value of the X&Y Axis and since the X Axis values are in date format, i have no idea how to add it to the setTooltipFormatString.