title: Adding a custom tooltip to a bubble chart / highchart
body: <p>I am trying to customize the tooltip in a highcharts bubble chart. Rather than having just the figures appear in the tooltip, I'd like to add context based on the x,y and z titles (ex, "50 fatalities, 100 injured, 150 total victims" instead of the current "(50,150) Size: 150" display). I'm able to make this happen in scatter plot charts using the following, but no dice in bubbles. Any ideas? Thanks. :)</p>
  
  <pre><code>tooltip: {
                      headerFormat: '&lt;b&gt;{series.name}&lt;/b&gt;&lt;br&gt;',
                      pointFormat: '{point.x} fatalities, {point.y} injured, {point.z}  total'
                  }
  </code></pre>