title: Updating EXTJS 4 Treepanel periodic
body: <p>I would like to create a <code>Treepanel</code>, which is updated once a second.
  So I took a store with a proxy for data acquistion:</p>
  
  <pre><code>store = new Ext.data.TreeStore({
      model: 'TaskState',
          proxy: {
          type: 'ajax',
          url : '/getTaskList'
  },
      root: {
          expanded: true
  }});
  </code></pre>
  
  <p>The store seems to work, the data is displayed in my <code>TreePanel</code>.</p>
  
  <p>I tried to update the <code>Treepanel</code> with this function:</p>
  
  <pre><code>function refresh(){
          store.load();
          window.setTimeout("refresh()", 1000);
      }
  </code></pre>
  
  <p>The update seems to work as well. Unfortunately the update causes some kind of "blinking" effekt on every update, because the whole tree is reloaded. I'm searching for a way to only refresh the nodes, which have changed.</p>
  
  <p>Is there some way to do this?</p>
  
  <p>greetings</p>