How do I get a tab in afterContent (in ListMarkerFormat)?

I've made this test:

package {
import flash.display.Sprite;
import flashx.textLayout.formats.TextLayoutFormat;
import flashx.textLayout.container.ContainerController;
import flashx.textLayout.elements.ParagraphElement;
import flashx.textLayout.elements.SpanElement;
import flashx.textLayout.elements.TextFlow;
import flashx.textLayout.elements.ListElement;
import flashx.textLayout.elements.ListItemElement;
import flashx.textLayout.formats.ListMarkerFormat;

public class ListTest3 extends Sprite
{
  public function ListTest3() {
   var textFlow:TextFlow = new TextFlow();
  
   var list:ListElement = new ListElement()
   list.listStyleType = "upperRoman";
   list.listStylePosition = "inside";
  
   var listMarkerFormat = new ListMarkerFormat();
   listMarkerFormat.beforeContent = "- ";
   listMarkerFormat.afterContent = "\t";

   var item:ListItemElement;
   item = new ListItemElement();
   item.listMarkerFormat = listMarkerFormat;
   var paragraphElement = new ParagraphElement();
   var spanElement = new SpanElement();
   spanElement.text = "Text starts here";
   paragraphElement.addChild(spanElement);
   item.addChild(paragraphElement);
   list.addChild(item);

   textFlow.addChild(list);

   var cs:Sprite = new Sprite();
   cs.x = 30;
   cs.y = 30;
  
   textFlow.flowComposer.addController(new ContainerController(cs, 400, 200));
   textFlow.flowComposer.updateAllControllers();
   addChild(cs);
  }
}
}

I works nicely, but when I try to add a tab after the numbering:

   listMarkerFormat.afterContent = "\t";

I don't gat a tab and also the numbering the beforeContent gets lost...

I've also tried 	 and \u0009, but they also did not work...

Or is it a problem that I haven't defined tabStops in the ListMarkerFormat?