anchor.diff:  <!-- la zone de dessin -->
   <div id="session-zone" data-role="page">
       <div data-role="header" data-id="head" data-backbtn="false" data-position="fixed">
  +        <a href="#" id="brush" class="ui-btn-left"><span id="brush-action">Show</span> colors</a>
           <h1>Drawing zone</h1>
           <a href="/logout" data-ajax="false" class="ui-btn-right">Logout</a>
           <div data-role="navbar">
  
positive.code:                 <li><a href="#session-chat">New messages<span class="ui-li-count">O</span></a></li>
              </ul>
          </div>
      </div>
  </div>
  <!-- la vue globale -->
  <div id="session-global" data-role="page">
  
negative.code:     <div data-role="content">
          <canvas id="session-drawing"></canvas>
      </div>
      <!--<div data-role="footer" data-position="fixed" class="ui-grid-d">
          <div class="ui-block-a">
              <a href="#" data-role="button" data-theme="c" id="brush"><span id="brush-action">Show</span> colors</a>
          </div>
  