title: How to change the url of a g:image in gwt
body: <p>I'm new to GWT.
  I created in my ui.xml a panel containing an Image.
  I want to change the url, the alt &amp; the title of that image depending some conditions. How to do it ?</p>
  
  <pre><code>&lt;g:Image url="images/document-statut-1.gif" title="My title" altText="My alt"&gt;&lt;/g:Image&gt;
  </code></pre>
  
  <p>Thnx</p>