title: How to conditionally close a jQuery Overlay?
body: <p>I am providing a custom close button for a jQuery Overlay.<br>
  When this button is clicked, I want to validate a form inside the Overlay, and close the Overlay <em>if and only if</em> the form is valid.</p>
  
  <p>Example (doesn't work... always close no matter what)</p>
  
  <pre><code>$('.trigger[rel]').overlay(
  {
     close: '.ovclosebutton',
     onClose: function()
     {
        if( validateSomething() )
            this.getOverlay().close();
        else
            displayErrorInOverlayButDontCloseIt(); 
     }
  });
  </code></pre>
  
  <p>How can I acheive this ?</p>