Checkbox Renderer Ignores Editable Property in a Grid Column

I've been having problems getting a Flex 3 checkbox to pay attention to a datagrid columns editable status. I finally found a solution using a component I had previously lifted from Alex's Flex Closet. The solution was in the code for the clickHandler - an override with a test of the parent columns editable status seems to have done the trick for me. This took me a while to work out - and even then there may be some issues with it. If anybody has a more efficient working method please let me know. I will come back soon and update this post with a full working example - but for now the code for extending the checkbox class is below.

package 
{
 
 import flash.display.DisplayObject;
 import flash.events.KeyboardEvent;
 import flash.events.MouseEvent;
 import flash.text.TextField;
 import mx.controls.CheckBox;
 import mx.controls.dataGridClasses.DataGridListData;
 import mx.controls.listClasses.BaseListData;
 import mx.controls.DataGrid;

 /** 
 *  The Renderer.
 */
 public class CentredCheckBox extends CheckBox
 {

  private var _listData:DataGridListData;

  public function CentredCheckBox()
  {
   focusEnabled = false;
  }
 
  override public function set data(value:Object):void 
  {
   super.data = value;
   if (listData is DataGridListData)
   {
    selected = Boolean(data[DataGridListData(listData).dataField]);
   }
  }
  override public function get listData():BaseListData
  {
   return _listData;
  }
  override public function set listData(value:BaseListData):void
  {
   _listData = DataGridListData(value);
  } 
 
  /* eat keyboard events, the underlying list will handle them */
  override protected function keyDownHandler(event:KeyboardEvent):void
  {
  }

  /* eat keyboard events, the underlying list will handle them */
  override protected function keyUpHandler(event:KeyboardEvent):void
  {
  }
 
  /* eat mouse events, the underlying list will handle them */
  /* unless we are in edit mode - in which case process them */
  override protected function clickHandler(event:MouseEvent):void
  {
   var allowEdit:Boolean;
   if (listData is DataGridListData)
   {
    allowEdit = DataGrid(DataGridListData(listData).owner).columns[DataGridListData(listData).columnIndex].editable;
   }
   if (allowEdit)
   {
    super.clickHandler(event);
   }
  }

  /* center the checkbox if we're in a datagrid */
  override protected function updateDisplayList(w:Number, h:Number):void
  {
   super.updateDisplayList(w, h);

   if (listData is DataGridListData)
   {
    var n:int = numChildren;
    for (var i:int = 0; i < n; i++)
    {
     var c:DisplayObject = getChildAt(i);
     if (!(c is TextField))
     {
      c.x = (w - c.width) / 2;
      c.y = 0;
     }
    }
   }
  }
 }
}