title: How to change Ext Js Button tooltip at runtime?
body: <p>I have the following:</p>
  
  <pre><code>var panel = headerPanel.add({
      id: 'recentcommands_button_id',
      xtype: 'button',
      text: "Recent Commands",
      tooltip: "Sample Tooltip Text"
  }); 
  </code></pre>
  
  <p>Followed later on by:</p>
  
  <pre><code>Ext.getCmp('recentcommands_button_id').tooltip = "TEST";
  </code></pre>
  
  <p>Which sets the tooltip value properly if I check the button's properties, but which does not actually change the value on the screen.</p>
  
  <p>I tried using:</p>
  
  <pre><code>Ext.getCmp('recentcommands_button_id').tooltip.update("TEST");
  </code></pre>
  
  <p>This did not work either.</p>
  
  <p>Any ideas?</p>