BIRT - How to add a dynamic marker?

I have one dataset and create from this set an area chart. In this case no problem. But now I have the requirement to add dynamic markers to the chart.

So, this is the example:

Data Set:
date | workload | type

The report renders开发者_Python百科 a chart, which displays the date on the x-Axis and the workload on the y-Axis. The Type shows the different areas in the chart.

Now I need an marker (line marker) which doesn't have a linear value, but therefore a value for each date which is displayed on the x-Axis.

On Birt-Exchange (http://www.birt-exchange.org/blog/2008-02-01/birt-chart-scripting-dynamic-markers/) is only a tutorial for static markers. So if anyone has an idea how to script this kind of marker, please feel free to answer ;-)

Thanks in advance!