code: function() {
                      //var graphPanelBox = d3.select("#graph-content-panel").node().getBoundingClientRect();
                      // top needs to be relative to the whole window
                      var ruleTop = topAxisBox.top;
                      var ruleHeight = totalAxesHeight + (perLineHeight * cMetrics.length);
                      // and now we just go find the rule we added and set the top/height
                      d3.select("#horizonRule_"+graph.id)
                          .select(".line")
                          .style("top", ruleTop+"px")
                          .style("height",ruleHeight+"px")
                          .style("bottom",null);
                  }
docs: .call(context.rule());