stickyTracking / trackByArea doesn't work when the tooltip has already appeared

[morganfree]

Expected behaviour

With disabled stickyTracking and trackByArea options for an area chart, the tooltip fires when the point is hovered.

Actual behaviour

Expected behaviour occurs when the tooltip has not been fired yet. If the tooltip is shown and the cursor is moving around the area then it causes that the tooltip jumps around the points.

Live demo with steps to reproduce

http://jsfiddle.net/z50ypuos/
Move the cursor inside the area - the tooltip doesn't show up unless the point is close.
Move the cursor inside the area when the tooltip is already shown up - the tooltip fires even when the point is "not close". It seems that tracking area is much bigger in this case.

[TorsteinHonsi]

The bug is that the tooltip doesn't hide if we leave the graph on to the area. It only hides if we leave the graph to the other side.

[pawelfus]

@TorsteinHonsi I am open if you have an idea for a test. I can test onTrackerMouseOut method with a fake event, but it doesn't really make sense..