I found how to find the leaf element with the following method but still do not know how to find the element that contains the selection.
/** Returns the current FlowELement element at the currentStyleLevel */
private function currentStyleElement(absolutePosition:int):FlowElement
{
var e:FlowElement;
switch(currentStyleLevel)
{
case TextFlow:
e = _textFlow;
break;
case ParagraphElement:
e = _textFlow.findLeaf(absolutePosition).getParagraph();
break;
default:
e = _textFlow.findLeaf(absolutePosition);
}
return e;
}