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:                     }
  
                      // Returns an event handler for fading a given chord group.
                      // Display parameter for the group hovering over
                      function fade(opacity, display) {
                          return function (d, i) {
                              // hide other chords on mose over
                              svg.selectAll("path.chord")
                                      .filter(function (d) {
                                          return d.source.index != i && d.target.index != i && (mpTopLevelTerms.indexOf(labels[d.source.index].name) < 0 && mpTopLevelTerms.indexOf(labels[d.target.index].name) < 0);
  