I think i've noticed a "bug" in treebolic source 2.0.3 - (released 20090210) which i checked out via CVS.
The Utils.java has a method called parseStyle which returns an IEdge.HIDDEN variable.
This IEdge.HIDDEN variable is declared in the IEdge.java as a byte, but in Utils.java an integer is expected.
I solved this by changing the variable declaration in IEdge.java from:
static public final byte HIDDEN = 0x1;

to

static public final int HIDDEN = 0x1;