Is there a good tutorial for Graphael (special line charts), I currently trying to implement such a graph with grafael http://www.highcharts.com/demo/?example=line-time-series&theme=default unfortunately there is no documentation.
A useful resource has been Kenny Shen's GitHub repository where he has begun writing up both documentation and examples for gRaphael.
https://github.com/qoelet/g.raphael
As an example check out the line chart documentation here