popUndo broken queue undo

{
    import flash.display.Sprite;
    import flash.display.StageAlign;
    import flash.display.StageScaleMode;
   
    import flashx.textLayout.container.ContainerController;
    import flashx.textLayout.conversion.TextFilter;
    import flashx.textLayout.edit.EditManager;
    import flashx.textLayout.edit.IEditManager;
    import flashx.textLayout.edit.IUndoManager;
    import flashx.textLayout.edit.SelectionState;
    import flashx.textLayout.elements.InlineGraphicElement;
    import flashx.textLayout.elements.InlineGraphicElementStatus;
    import flashx.textLayout.elements.TextFlow;
    import flashx.textLayout.events.StatusChangeEvent;
    import flashx.textLayout.formats.Float;
    import flashx.textLayout.formats.TextLayoutFormat;
    import flashx.textLayout.operations.InsertInlineGraphicOperation;
    import flashx.undo.UndoManager;

    public class InlineGraphicUndoRedo extends Sprite
    {
        private static const markup:String = '<?xml version="1.0" encoding="utf-8"?><TextFlow fontSize="14" paddingBottom="inherit" lineBreak="inherit" paddingTop="4" textIndent="15" verticalAlign="inherit" paddingRight="inherit" paddingLeft="4" whiteSpaceCollapse="preserve" xmlns="http://ns.adobe.com/textLayout/2008"><p marginBottom="15">This is some textttt.</p></TextFlow>';
       
        public function InlineGraphicUndoRedo()
        {
            super();
           
            stage.scaleMode = StageScaleMode.NO_SCALE;
            stage.align = StageAlign.TOP_LEFT;

               var s:Sprite;
              
               s = new Sprite()

              addChild(s);
              s.x = 10;
              s.y = 200;
              var textFlow:TextFlow = fillComposer(markup,s);
             
              var em:IEditManager = textFlow.interactionManager as IEditManager;
            var selState:SelectionState = new SelectionState(textFlow,1,1);
            em.doOperation(new InsertInlineGraphicOperation(selState,'http://tarrascao.files.wordpress.com/2008/12/universo_digital.jpg',214,140,Float.NONE));
           
            var img:InlineGraphicElement = textFlow.findLeaf(1) as InlineGraphicElement;
           
            var cf:TextLayoutFormat = new TextLayoutFormat();
            cf.lineHeight = 100;    
           
            var um = EditManager(textFlow.interactionManager).undoManager;
           
            trace(um.peekUndo())
            EditManager(textFlow.interactionManager).applyLeafFormat(cf,
            new SelectionState(textFlow, img.getAbsoluteStart(), img.getAbsoluteStart()+1));
            textFlow.flowComposer.updateAllControllers();           
            trace(um.peekUndo());
           
            um.popUndo();  // whether comment this line, works, but is not what I need

                       
            trace(um.peekUndo())
           
            textFlow.flowComposer.updateAllControllers();
        }

          private function fillComposer(markup:String,s:Sprite):TextFlow   
          {
              var textFlow:TextFlow = TextFilter.importToFlow(markup, TextFilter.TEXT_LAYOUT_FORMAT);
              var controller:ContainerController = new ContainerController(s,400,400);
              textFlow.flowComposer.addController(controller);
              textFlow.flowComposer.updateAllControllers();
              textFlow.interactionManager = new EditManager(new UndoManager());
              textFlow.addEventListener(StatusChangeEvent.INLINE_GRAPHIC_STATUS_CHANGED,graphicLoaded);
              return textFlow;
          }
         
          static private function graphicLoaded(evt:StatusChangeEvent):void
          {
              if (evt.status == InlineGraphicElementStatus.SIZE_PENDING || evt.status == InlineGraphicElementStatus.READY)
                  evt.element.getTextFlow().flowComposer.updateAllControllers();
          }

    }
}