title: adding multiple functions to an ExtJS gridPanel button's handler
body: <p>I have an ExtJS gridPanel with a button that fires a global function:</p>
  
  <pre><code>grid = Ext.create('Ext.grid.Panel', {
  ...
      tbar: [
          {
              xtype: 'button',
              text: 'Group',
              handler: group // call to global function
          }
      ]
  ...
  });
  </code></pre>
  
  <p>After I have called the <code>group</code> function, I need to call another global function, for instance <code>renameGroups</code>; how do I place this function, or indeed any additional functions, in the handler?</p>