title: How to allow installation only to a specific folder?
body: <p>I would like to install my setup content only to one specific directory, so I want to have the <code>Next</code> button on directory selection page disabled, unless the user chooses the right folder to install to.</p>
  
  <p>How can I disable the <code>Next</code> button on directory selection page and enable it right after user chooses a specific directory ?</p>