protected VisualTable getTable() {
TupleSet ts = m_vis.getGroup(m_group);
if ( ts == null ) {
Schema s = PrefuseLib.getAxisLabelSchema();
VisualTable vt = m_vis.addTable(m_group, s);
vt.index(VALUE);
return vt;
} else if ( ts instanceof VisualTable ) {
return (VisualTable)ts;
} else {
throw new IllegalStateException(