Tooltip caret not drawn after updating `tooltip.options.shared` dynamically

[havgry]

Expected behaviour

The tooltip is drawn according to the current state of shared (in this case when the tooltip isn't shared) in the same way it is with e.g. backgroundColor.

Actual behaviour

The shared property is updated and working accordingly but the caret is no longer drawn.

Live demo with steps to reproduce

http://jsfiddle.net/dm2fLhan/

1. The tooltip is not shared and a caret is visible
2. Click the toggle button
3. The tooltip is now shared and no caret is displayed (as expected)
4. Click the toggle button again
5. The shared property is now back to its initial value (false) but the caret is gone

Affected browser(s)

All. Issue is not browser specific.

[pawelfus]

Thanks for reporting!

Workaround:
Set chart.tooltip.len = null; before updating the tooltip. Demo: http://jsfiddle.net/3va712y2/

Internal note:
In tooltip.refresh() method tooltip.len is always set for a shared tooltip, but never for a non-shared tooltip.