A: 

I'm not sure you can do that in JFreeChart.

A solution (which is not nice) is to render the chart to an image and then manipulate it (chop it up etc.) as an image, using RenderedImage, and not as a JFreeChart. Unfortunately that's going to be a bit of a pain since you'd probably want to chop at a particular place on the y-axis etc.

Brian Agnew
+4  A: 
pjp
Great, that looks exactly as wished, thanks for the fast help.
Mnementh