title: Extjs 3.4 problems rendering buttons in toolbar
body: <p>Using Extjs 3.4. I am creating a top Toolbar above a grid. </p>
  
  <pre><code>Ext.onReady(function() {
      var colModel = new Ext.grid.ColumnModel({
          columns: [{
              header: "Sottogruppo",dataIndex: 'some'
          }],
          defaults: {
              width: 50,
              sortable: false
          }
      });
  
      var saveButton = new Ext.Button({text: "Salva",id: 'save'});    
  
      var tbar = new Ext.Toolbar({items: [saveButton]});
  
      var grid = new Ext.grid.EditorGridPanel({
          colModel: colModel,
          tbar: tbar
      });
      grid.render("grid");
  });
  </code></pre>
  
  <p>The chrome console show this error: </p>
  
  <pre><code>Uncaught TypeError: Cannot read property 'getSortState' of undefined ../JS/ext-3.3.1/ext-all-debug.js
  </code></pre>
  
  <p>Ideas?</p>
  
  <p><strong><em>SOLUTION</em></strong>
  add a store in the grid config: </p>
  
  <pre><code>store: new Ext.data.ArrayStore()
  </code></pre>