tooltip.split datetime tooltip cut off

[jschuler]

Expected behaviour

I like the new tooltip.split option. But I noticed an issue when hovering over data points at the far left or far right of the graph.
I would expect the datetime tooltip that is on the x-axis to shift inwards when it would otherwise flow outside the chart box.

Actual behaviour

Datetime tooltip box does not shift inwards when hovering over the far right point.

Live demo with steps to reproduce

http://jsfiddle.net/gh/get/jquery/1.7.2/highcharts/highcharts/tree/master/samples/highcharts/tooltip/split/
Hover all the way to the right. You can see that the datetime tooltip at the bottom gets cut off to the right.

Affected browser(s)

Tested in chrome