title: Positioning / Scrolling problem with Flex popup
body: <p>I'm trying to work out a specific problem I'm having with positioning in Flex using the PopUpManager. Basically I'm wanting to create a popup which will scroll with the parent container - this is necessary because the parent container is large and if the user's browser window isn't large enough (this will be the case the majority of the time) - they will have to use the scrollbar of the container to scroll down. The problem is that the popup is positioned relative to another component, and it needs to stay by that component.</p>
  
  <pre><code>&lt;?xml version="1.0" encoding="utf-8"?&gt;
  &lt;mx:Application xmlns:mx="http://www.adobe.com/2006/mxml" layout="absolute"&gt;
  
    &lt;mx:Script&gt;
      &lt;![CDATA[
        import mx.core.UITextField;
        import mx.containers.TitleWindow;
        import mx.managers.PopUpManager;
  
        private function clickeroo(event:MouseEvent):void {
          var popup:TitleWindow = new TitleWindow();
          popup.width = 250;
          popup.height = 300;
  
          popup.title = "Example";
          var tf:UITextField = new UITextField();
          tf.wordWrap = true;
          tf.width = popup.width - 30;
          tf.text = "This window stays put and doesn't scroll when the hbox is scrolled (even with using the hbox as parent in the addPopUp method), I need the popup to be local to the HBox.";
          popup.addChild(tf);
  
          PopUpManager.addPopUp(popup, hbox, false);
          PopUpManager.centerPopUp(popup);
        }
      ]]&gt;
    &lt;/mx:Script&gt;
  
    &lt;mx:HBox width="100%" height="2000" id="hbox"&gt;
      &lt;mx:Button label="Click Me" click="clickeroo(event)"/&gt;
    &lt;/mx:HBox&gt;
  
  &lt;/mx:Application&gt;
  </code></pre>
  
  <p>Could anyone give me any pointers in the right direction? Thanks.</p>