How to get proper value of .contentHeight after scaling? content of s:Group

Question

<?xml version="1.0" encoding="utf-8"?>
<s:BorderContainer
    xmlns:fx="http://ns.adobe.com/mxml/2009" 
    xmlns:s="library://ns.adobe.com/flex/spark" 
    creationComplete="creationCompleteHandler(event)"
    xmlns:mx="library://ns.adobe.com/flex/mx" 
    mouseWheel="mouseWheelHandler(event)"
    backgroundAlpha="0"
    width="100%" 
    height="100%">
    <fx:Script> 
        <![CDATA[
            import com.luaye.console.C;

            import flash.events.MouseEvent;

            import flashx.textLayout.formats.BackgroundColor;

            import mx.controls.ToolTip;
            import mx.core.FlexGlobals;
            import mx.core.IUIComponent;
            import mx.core.UIComponent;
            import mx.events.FlexEvent;
            import mx.events.PropertyChangeEvent;
            import mx.graphics.SolidColor;
            import mx.graphics.SolidColorStroke;
            import mx.managers.ToolTipManager;





            protected function creationCompleteHandler(event:FlexEvent):void
            {

            }           

            protected function mouseWheelHandler(event:MouseEvent):void
            {
                if ( event.delta > 0 ) {                    
                    mapContainer.scaleX += 1;
                    mapContainer.scaleY += 1; 
                } else {
                    mapContainer.scaleX = mapContainer.scaleY -=1;                  
                }  

                trace(test.contentHeight); // 30
            }
        ]]>
    </fx:Script>
    <fx:Declarations>
        <!-- Place non-visual elements (e.g., services, value objects) here -->
    </fx:Declarations>

    <s:Label y="30" text="{test.contentHeight}" /> <!-- 60 -->
    <s:Group id="test" width="100%" height="100%" clipAndEnableScrolling="true" >
        <s:Group id="mapContainer"  />
            <s:Label text="test" />
    </s:Group>          
</s:BorderContainer>

How to get proper value of .contentHeight after scaling?

Thank you!