Need a way to calculate the width of a Label that has been cut off by truncation

I have a Label that is being truncated with an ellipsis mark (...) and I would like to programmatically figure out how much width is being cut off.

In Group I would do something like (group.contentWidth - group.width), but there does not seem to be an equivalent concept in Label.

Example use case:

<s:Application xmlns:fx="http://ns.adobe.com/mxml/2009"
xmlns:s="library://ns.adobe.com/flex/spark">
<fx:Script>
<![CDATA[
public function figureOutExcess():void

{ // i want to know how much of this Label is being hidden behind the ... // Ideally something like ... // trace(lbl.contentWidth - lbl.width); }

]]
>
</fx:Script>

<s:Label id="lbl" width="100" maxDisplayedLines="1" text="Some long string which will get ellipsis'd" />
</s:Application>

Workaround:

From Gordon: "I don't think there is a property that tells you the untruncated width. I think you'd first have to set width to NaN and maxDisplayedLines to 0 in order to get the Label to render the text untruncated in a single line, wait for the updateComplete event, and read the measuredWidth. That should be the untruncated width. Then you could set width to 100 and maxDisplayedLines to 1."