anchor.diff:                              })
                               .enter().append("g")
                               .attr("class", "group")
  -                            .on("mouseover",  fade(.02))
  -                            .on("mouseout",  fade(.80))
  +//                            .on("mouseover",  fade(.02, "visible"))
  +//                            .on("mouseout",  fade(.80, "hidden"))
                               .on("click", function(d){
                                   window.open(url + "&phenotype_name=" + labels[d.index].name , "_self" );
                               });
  
positive.code:                                     .transition()
                                      .style("stroke-opacity", opacity)
                                      .style("fill-opacity", opacity);
                          };
                      }
                  }
  
negative.code:                             })
                              .style("stroke", function (d) {
                                  return d3.rgb(color(d.target.index)).darker();
                              })
                              .style("visibility", function(d){
                                  if (mpTopLevelTerms.indexOf(labels[d.source.index].name) < 0 && mpTopLevelTerms.indexOf(labels[d.target.index].name) < 0) {
                                      return "hidden";
                                  } else {
                                      return "visible";
                                  }
                              })
                              .append("title").text(function (d) {
                          return d.source.value + " genes present " + labels[d.source.index].name + " and " + labels[d.target.index].name + ", " + mpTopLevelTerms.join(", ");
  