title: Using responsive plugin in ExtJS 5
body: <p>I have used extjs responsive plugin as below to make a responsive data grid.</p>
  
  <pre><code> plugins: 'responsive',
   responsiveConfig: {
      'width &lt; 600': {
      width: 150
      },
      'width &gt;= 600': {
      width: 320
      }
  }
  </code></pre>
  
  <p>But what I actully need is dinamically change the width according to the viewport size. Something like this.</p>
  
  <pre><code>responsiveConfig: {
          width: getViewPortsize()/2
      }
  </code></pre>
  
  <p>How can I actually do this?</p>