title: Highstocks dynamic graph - timeslider graph pattern issue
body: <p>I am using Highstocks dynamic graph with time slider something similar to <a href="http://jsfiddle.net/gh/get/library/pure/highcharts/highcharts/tree/master/samples/stock/demo/dynamic-update/" rel="nofollow noreferrer"> here</a></p>
  
  <p><div class="snippet" data-lang="js" data-hide="false" data-console="true" data-babel="false">
  <div class="snippet-code">
  <pre class="snippet-code-js lang-js prettyprint-override"><code>Highcharts.setOptions({
      global: {
          useUTC: false
      }
  });
  
  // Create the chart
  Highcharts.stockChart('container', {
      chart: {
          events: {
              load: function () {
  
                  // set up the updating of the chart each second
                  var series = this.series[0];
                  setInterval(function () {
                      var x = (new Date()).getTime(), // current time
                          y = Math.round(Math.random() * 100);
                      series.addPoint([x, y], true, true);
                  }, 1000);
              }
          }
      },
  
      rangeSelector: {
          buttons: [{
              count: 1,
              type: 'minute',
              text: '1M'
          }, {
              count: 5,
              type: 'minute',
              text: '5M'
          }, {
              type: 'all',
              text: 'All'
          }],
          inputEnabled: false,
          selected: 0
      },
  
      title: {
          text: 'Live random data'
      },
  
      exporting: {
          enabled: false
      },
  
      series: [{
          name: 'Random data',
          data: (function () {
              // generate an array of random data
              var data = [],
                  time = (new Date()).getTime(),
                  i;
  
              for (i = -999; i &lt;= 0; i += 1) {
                  data.push([
                      time + i * 1000,
                      Math.round(Math.random() * 100)
                  ]);
              }
              return data;
          }())
      }]
  });</code></pre>
  <pre class="snippet-code-html lang-html prettyprint-override"><code>&lt;script src="https://code.highcharts.com/stock/highstock.js"&gt;&lt;/script&gt;
  &lt;script src="https://code.highcharts.com/stock/modules/exporting.js"&gt;&lt;/script&gt;
  
  &lt;div id="container" style="height: 400px; min-width: 310px"&gt;&lt;/div&gt;</code></pre>
  </div>
  </div>
  </p>
  
  <p>The only difference I have is that I can have 1 to n number of lines in the graph which will keep on updating after a particular time period. Now my question is </p>
  
  <ol>
  <li>Although I have multiple line graphs plotted on the top but I see only one line graph in the bottom of the graph inside my time slider. Is it expected or the time slider should also have the same number of graphs as on top of the graph?</li>
  <li>What does the line graph inside the time slider on the bottom of the graph signifies? I can't see the pattern of the bottom graph similar to any of my top graph pattern. Does high chart takes the union of all the top graphs and then constructs one single bottom graph pattern or is there any other logic for the pattern of the bottom time slider graph.Pls, explain.</li>
  </ol>
  
  <p>Thanks in Advance!</p>