Graph plotting and labels

[VictorMiller]

I'm in the middle of implementing SAGE classes for binary decision
diagrams using the library called CUDD (which is included in
Polybori). Each BDD is actually a labeled DiGraph. It's standard in
the BDD literature to draw pictures of the digraph as follows:

the vertex label of a non-leaf is a decision node, and it's standard
to label it with the variable name. Note that the same variable may
appear in more than one node, so this is not the same as the vertex
labeling convention for DiGraph in sage. Each decision node also
always has two outgoing directed edges -- the true edge which is drawn
with a solid line, and the false edge with a dotted line. Is there a
way in the plotting package from graph to have different edge
rendering depending on some criterion? It would also be nice if the
graph package could be supplemented to allow extra labels to be
associated with each vertex (besides its unique label), and to have an
option for plot of just printing the extra information. It's also
traditional in the BDD literature to print the leaves (terminal nodes)
with boxes around them instead of circles.

What do people think about some way of enriching the graph package to
allow such things?

Victor