NickQiZhu/dc.js — pull request #321 by sclevine (2013-10-07 22:30:01+00:00)
Title: Tooltip elements should be drawn on top of chart paths

Tooltip dots and ref lines need to be drawn on top of other chart elements such as areas and lines.
To accomplish this, we've moved tooltip elements into a separate container.
This change is only applicable to stacked line graphs.