title: Highcharts: Corner radius for plot border
body: <p>Is there a way to provide a corner radius value for "plot border"?
  Looking for something similar to the borderRadius option for the chart border. But we need it for the plot border.</p>
  
  <p>I tried doing adding radius after loading the chart with the below but it does not work</p>
  
  <pre><code>chart.plotBorder.rx=5;
  chart.plotBorder.ry=5;
  chart.redraw();
  </code></pre>
  
  <p>Appreciate any help
  Thanks.</p>