title: User Interface Markup Language pros and cons
body: <p>I learnt about some declarative UI languages such as <a href="http://en.wikipedia.org/wiki/Xul" rel="nofollow noreferrer">XUL</a> for Mozilla/Gecko and <a href="http://en.wikipedia.org/wiki/HTML_Application" rel="nofollow noreferrer">HTA</a> for Microsoft at Wikipedia.    </p>
  
  <ul>
  <li>What would be the
  advantages/disadvantages of these
  markup languages?</li>
  <li>Why don't common OSes and
  Applications use these techniques?</li>
  <li>Do these languages impart flexibility
  to the system?</li>
  <li>Are there any OSes that use markup
  languages for displaying their UI if
  not why?...<br>
  Examples of these OSes
  or Applications however ancient they may be would be welcome..</li>
  </ul>