Scroller fixed at bottom

Question

I am having a RichEditableText field fich gets filled with text dynamically. There is a vertical scroller attached to it which should behave exactly the opposite way as it does.
I need to have it to stick to the bottom the field, displaying the last line. However this does not work.
My setup is as follows:
I am having a text input field to enter text.
I am having the RichEditableText field surrounded by the <s:scroller> control.
And I set the VerticalScrollPosition of the scroller to the RichEditableText content.height.
Now this is what is happening and it is really weird:
When entering text it gets displayed properly. When I have entered a few lines the vertical scroll bar appears as intended. But then the scrollbar does no longer get updated with every new line entered. In fact it only gets updated every 3 new line. Then it stick to the bottom for 1 input and then it pauses for 3 more inputs. It is very weird.
When I set it to listen to the updateCompete event of the RichEditableText field and set the VerticalScrollPosition of the scroller to the RichEditableText content.height it works as intended and the scrollbar remains at the bottom. However now scrolling is no longer possible as every attempt to scroll causes the update event to get fired, thus bouncing the scrollbar back to the content height value.
So it seems that one solution could be to find another event that is fired when the RichEditableText field has been updated, but does not fire when the scrollbar is the reason for updating, or to prevent the updateCancel Event to fire when the field has been updated due to scrolling.
Or there is a totally different approach to get this working. But I was not able to get it working the way I need it yet. Any help or hints would be appreciated.
Here is the code of what I am doing:
MXML part:
<s:Scroller id="vscroller" width="100%" height="100%" horizontalScrollPolicy="off">
<s:RichEditableText height="100%" width="100%" id="ret" updateComplete="ret.verticalScrollPosition=ret.contentHeight;"/>
</s:Scroller>
Actionscript part:
flow = TextConverter.importToFlow(message, TextConverter.TEXT_FIELD_HTML_FORMAT) as TextFlow;
paragraph = flow.getChildAt(0) as ParagraphElement;
ret.textFlow.addChild(paragraph);
ret.textFlow.flowComposer.updateAllControllers();

Answer 1

if anyone still need a solution:
you should attach event listener to RichEditableElement before adding new text line, then catch event and update scroller.verticalScrollBar.value to it's maximum. the reason is you update scroll position before text area changed and completely updated, but you should do this after. example follows:
     chatTextArea.addEventListener(mx.events.FlexEvent.UPDATE_COMPLETE, onChatTextAreaChanged);
     chatTextArea.textFlow.addChild(line);
public function onChatTextAreaChanged(event:*):void {
     chatTextArea.removeEventListener(mx.events.FlexEvent.UPDATE_COMPLETE, onChatTextAreaChanged);
     chatTextScroller.verticalScrollBar.value = chatTextScroller.verticalScrollBar.maximum;