title: Layout run failed when adding `locked:true` to `actionColumn`
body: <p>I need a action column to be locked in postion and size. Therefore I thought is the <code>locked</code> property but as soon as I add it I get the</p>
  
  <blockquote>
    <p>[E] Layout run failed</p>
  </blockquote>
  
  <p>error for each row to render. What do I wrong or is this a bug?</p>
  
  <p>I am using ExtJS 4.2.1</p>
  
  <pre><code>{
      layout: 'hbox',
      border: false,
      xtype: 'container',
      items: [
          {
              xtype: 'grid',
              shrinkWrapDock: true,
              flex: 1,
              store: store,
              minHeight: 300,
              title: 'Test',
              columns: [
                  { xtype:'actioncolumn', locked: true, sortable: false, hideable: false, dataIndex: 'Aktiv', width: 20, items: [{
                          tooltip: 'deactivate', 
                          handler: function(view,row,col,item,ev,rec,row) {
                              rec.data.set('Active',!rec.data.get('Active'));
                          } 
                      }]
                  },
                  // more columns
              ]
          }
      ]
  }
  </code></pre>