title: Suitable GUI framework for Scala?
body: <p>By suitable, I mean:</p>
  
  <ul>
  <li>mature and used extensively</li>
  <li>rich widget set that renders well</li>
  <li>idiomatic Scala</li>
  <li>Got a WYSIWYG-ish but flexible GUI builder</li>
  <li>standalone API documentation (if a wrapper, it shouldn't make me refer the parent project in another language)</li>
  </ul>
  
  <p>In no particular order.</p>
  
  <p>Which GUI toolkits satisfy which conditions?</p>