title: Flex: Disable ContextMenu customItems on AdvancedDataGrid headers
body: <p>How can I disable or hide ContextMenu customItems when a user right-clicks on a header? I tried to set customItems to an empty array:</p>
  
  
  
  <pre><code>class MyAdvancedDataGridHeaderRenderer
       extends AdvancedDataGridHeaderRenderer {
    protected function onComplete(event:FlexEvent) {
      contextMenu.customItems = [];
    }
  }
  </code></pre>
  
  <p>...but the contextMenu for the header is null.</p>