title: Focus a editable grid's row within the form
body: <p>I have a editable grid (<code>Ext.grid.plugin.RowEditing</code>)
  The grid is with in a form. The form is shown in a window</p>
  
  <p>As the form is shown by showing the window, i want to focus on the first editable row's first column.</p>
  
  <p>This is the method called for window's 'show' event</p>
  
  <pre><code>onWinShow : function (window, options) {
  
      var grid = this.down ('#myGrid');
      // focus on first field
      var rowEditStore = grid.getStore ();
      var rowEditor = grid.getPlugin ('rowEditplugin');
  
      rowEditor.cancelEdit ();
  
      var r = rowEditStore.getAt (0);
      rowEditor.startEdit (r, 1);
  },
  </code></pre>
  
  <p>I checked the source of <code>RowEditing</code> and <code>RowEditor</code> which has the logic for focusing the field.
  I can see the focus appearing for a moment and then vanishing, No field in the form is focused after that.</p>
  
  <p>Please suggest where have i gone wrong.</p>
  
  <p>Thanks</p>