title: Editing a line in an ExtJs grid
body: <p>Hello, I'm developing a project using Ext Js that needs to edit a line in a grid. I'm trying to use a plugin I found in Ext's documentation, plugins: [Ext.create ('Ext.grid.plugin.RowEditing')] but when I click on the line, update and cancel options appear on the grid, but the cell is not editable, does anyone know what's going on?</p>
  
  <p>The example in the documentation with the plugin is this: <a href="http://docs.sencha.com/ext-js/4-0/#!/example/restful/restful.html" rel="nofollow">http://docs.sencha.com/ext-js/4-0/#!/example/restful/restful.html</a></p>
  
  <p>My code so far:</p>
  
  <pre><code>Ext.define('GridEditavel',{
  
  extend : 'Ext.grid.Panel',
  title: 'Grid Editavel',
  store: 'GridStore',
  dockedItems : [ {
      xtype : 'toolbar',
      items : [ {
          xtype: 'button',
          text : i18n['vds.botao.nova.coluna'],
          icon : Webapp.icon('add1.png'),
          iconAlign : 'top',
          handler : function() {
              var gridView = Ext.ComponentQuery.query("gridpanel")[1];
              Ext.Msg.prompt('Message', 'Enter a column number:', function(
                      btn, text) {
                  if (btn == 'ok' &amp;&amp; text != null) {
                      var column = Ext.create('Ext.grid.column.Column', {
                          text : text
                      });
                      gridView.headerCt.insert(gridView.columns.length,
                              column);
                      gridView.getView().refresh();
                  } else {
                      Ext.Msg.alert('Alert', 'Enter a column number!');
                  }
              });
          }
      } ]
  } ],
  columns: [{
      header : 'Nome',
      dataIndex : 'nome',
      flex : 0.8
  }],
  
  plugins : [ Ext.create('Ext.grid.plugin.RowEditing') ]});
  </code></pre>