title: Why use s:Line instead of mx:HRule?
body: <p>When using a <strong>mx:HRule</strong> or <strong>mx:VRule</strong>, Flash Builder suggests using a <strong>s:Line</strong> instead. 
  Why would I want to write stuff like this : </p>
  
  <pre><code>&lt;s:Line xFrom="0" xTo="245" yFrom="0" yTo="1"/&gt;
  </code></pre>
  
  <p>instead of </p>
  
  <pre><code>&lt;mx:Hrule width="100%" /&gt;
  </code></pre>
  
  <p>How do I get relative sizes ? (percent)</p>