square box graph (?) API in python

[Astan Chee]

Hi,
I'm trying to graph something that looks like the bottom half of this 
http://windirstat.info/images/windirstat.jpg
I was wondering if there is any API in python or wxPython specifically 
to do this?
I know it is possible to do calculation manually and use floatcanvas or 
something similar but I was wondering if something like this has already 
been done.
Cheers
Astan