Strange Panel titlebar Error in Flashbuilder4

Question

I'm getting an error in Flashbuilder4 in the debug windows that says:
Main Thread (Suspended: ReferenceError: Error #1069: Property titleBar not found on mx.containers.Panel and there is no default value.)
But at the exact same time, in the same debugging session, in the expressions window, the object evaluates properly:
ctx.mainPanel.titleBar.height = 24 [0x18]
Panel.getHeaderHeight also fails.  Is this a bug in Flashbuilder4?

Answer 1

1) In main.mxml I have this markup:
<mx:Script source="com/mag/ascript/Update.as"/>
<observer:ObserveValue source="{model.app.dirtyUI}" handler="updateUI" value="true"/>
<mx:Panel id="mainPanel" ...
2) In Update.as I have:
public function updateUI():void      // not in a class
    SummaryViewReport.doReport(this);
3) In SummaryView class I have:
    static public function doReport(ctx:Object):void
        var x:Number = ctx.mainPanel.titleBar.height;  <-- Error
I can't see it as human error if the expressions window correctly evaluates the value and the debug window reports that titleBar is not found on ctx.mainPanel in the same debug run. I can also reference other items on ctx.mainPanel without a problem.