title: D3 pie chart updating issue, increasing size of focused slice
body: <p>I'm building a pie chart with D3 that can be updated with new information, and that also has a couple cool features. </p>
  
  <p>Currently the pie chart functions just fine, but I'm having trouble with increasing the size of whichever slice has the mouse on top of it. I have done this: </p>
  
  <pre><code>cv_path.enter()
    .append("path")
    .attr("fill", function(d, i) { return cv_color(i); } )
    .attr("d", cv_arc)
    .each(function(d) { this._current = d; })
    .attr("stroke","white")
    .attr("stroke-width",1)
    .on("mouseenter", function(d) {
      d3.select(this)
        .transition()
        .duration(350)
        .attr("d", arcOver)
        .attr("stroke","white")
        .attr("stroke-width",1);
    })
    .on("mouseleave", function(d) {
      d3.select(this).transition()
        .attr("d", arc)
        .attr("stroke","none")
        .attr("stroke","white")
        .attr("stroke-width",1);
  </code></pre>
  
  <p>Please forgive the duplication, I'm just trying to get things functioning. So, this actually works like I intended, but I ran into a problem. When the pie chart updates/transitions to represent the updated data it no longer keeps the chunk enlarged. It updates and acts as if my mouse is no longer there until I move it again. Is there a way where, when the graph updates, I can keep the chunk enlarged? </p>
  
  <p>Here is a jsfiddle to illustrate my problem: <a href="http://jsfiddle.net/22o1epyp/" rel="nofollow">http://jsfiddle.net/22o1epyp/</a></p>
  
  <p>If you hover your mouse over a slice it will enlarge, and once the graph updates you will notice that no slice is enlarged. This is the issue.</p>