title: How to get current drilldown's id in Highcharts
body: <p>I have a drilldown Highcharts graph as follow:</p>
  
  <pre><code>$('#container').highcharts({
      chart: {
          type: 'column'
      },
      title: {
          text: 'Basic drilldown'
      },
      xAxis: {
          type: 'category'
      },
      series: [{
          name: 'Things',
          colorByPoint: true,
          data: [{
              name: 'Animals',
              y: 5,
              drilldown: 'animals'
          }, {
              name: 'Fruits',
              y: 2,
              drilldown: 'fruits'
          }, {
              name: 'Cars',
              y: 4,
              drilldown: 'cars'
          }]
      }],
      drilldown: {
          series: [{
              id: 'animals',
              data: [
                  ['Cats', 4],
                  ['Dogs', 2],
                  ['Cows', 1],
                  ['Sheep', 2],
                  ['Pigs', 1]
              ]
          }, {
              id: 'fruits',
              data: [
                  ['Apples', 4],
                  ['Oranges', 2]
              ]
          }, {
              id: 'cars',
              data: [
                  ['Toyota', 4],
                  ['Opel', 2],
                  ['Volkswagen', 2]
              ]
          }]
      }
  });
  </code></pre>
  
  <p>You can have a look at it here:<a href="http://jsfiddle.net/gh/get/jquery/1.7.2/highslide-software/highcharts.com/tree/master/samples/highcharts/drilldown/basic/" rel="nofollow">JSFiddle link</a>.</p>
  
  <p>When user selects a column and the drilldown chart is displayed, how do I get the current drilldown's id and data?</p>
  
  <p>Thanks in advance.</p>