title: display 2nd form depending on 1st form result
body: <p>I have two form in the same Tapestry page's:</p>
  
  <p>First one is composed of :</p>
  
  <ul>
  <li>select </li>
  <li>submit button.</li>
  </ul>
  
  <p>If there is a valid result I display it.</p>
  
  <p>Otherwise I want to display the 2nd form wich is composed of :</p>
  
  <ul>
  <li>4 textfields</li>
  <li>1 submit button</li>
  </ul>
  
  <p>So the 2nd must not be displayed first time, but only in case of empty result from the 1st one.</p>