title: C3.js making line appear dashed
body: <p>I am using C3.js using two Y axis. I have 2 data series:</p>
  
  <pre><code>data: {
          rows: [
          ['data1', 'data2', 'data3'],
          [90, 120, 300],
          [40, 160, 240],
          [50, 200, 290],
          [120, null, 230],
          [80, null, 300],
          [90, null, 320],
      ],
          regions: {
              'data1': [{'start':0, 'style':'dashed'},],
          }
      }
  </code></pre>
  
  <p>When I run this I get a dashed line and then it graphs null as a dashed line along the x axis. This is not what I want. I want it to stop graphing when the data set is null. If I remove the region I get the functionality I desire but I do not get the dashed line.</p>
  
  <p>Is there a way to get the dashed line without graphing the null values?</p>