在工具提示中添加按钮

目前，我正在使用这个服务器监控:

http://bl.ocks.org/d3noob/9692795

问题是，我不知道如何在工具提示中添加按钮(开始，停止)

我已经完成了d3js工具提示doc:

http://www.d3noob.org/2013/01/adding-tooltips-to-d3js-graph.html

但是不能这样做。有谁能帮帮我吗?

当前代码:

// Enter any new nodes at the parent's previous position.
var nodeEnter = node.enter().append("g")
    .attr("class", "node")
    .attr("transform", function(d) {
        return "translate(" + source.y0 + "," + source.x0 + ")"; })
            .on("click", click)
            // add tool tip for ps -eo pid,ppid,pcpu,size,comm,ruser,s
            .on("mouseover", function(d) {
                div.transition()
                    .duration(200)
                    .style("opacity", .9);
                    div .html(
                        "PID: " + d.name + "<br/>" + 
                        "Command: " + d.COMMAND + "<br/>" +
                        "User: " + d.RUSER + "<br/>" +
                        "%CPU: " + d.CPU + "<br/>" +
                        "Memory: " + d.SIZE
                    )
                    .style("left", (d3.event.pageX) + "px")
                    .style("top", (d3.event.pageY - 28) + "px");
            })
            .on("mouseout", function(d) {
                div.transition()
                    .duration(500)
                    .style("opacity", 0);
            });