why generic spark checkbox "symbolColor" gives Code Navigation Error: Source could not be found?

[mo...@comcast.net]

I'm trying to run this simple test program (to debug changing the symbolColor in my application): 

<?xml version="1.0" encoding="utf-8"?> 
<!-- http://blog.flexexamples.com/2009/03/30/setting-the-base-color-on-an-fxcheckbox-control-in-flex-gumbo/ --> 
<s:Application xmlns:fx=" http://ns.adobe.com/mxml/2009 " 
xmlns:s=" library://ns.adobe.com/flex/spark " 
xmlns:mx=" library://ns.adobe.com/flex/mx " minWidth=" 955 " minHeight=" 600 " > 

<s:CheckBox id=" checkBox " 
label=" Spark CheckBox " 
selected=" true " 
symbolColor=" red " 
horizontalCenter=" 0 " 
verticalCenter=" 0 " /> <!-- baseColor="black" --> 

</s:Application> 


I'm using Flash Builder 4.7 and SDK 4.6 or 4.11, and while it seems to run fine, if I command-click on the "symbolColor" code then click on it when it underlines, I get the error message:

   Code Navigation Error: Source could not be found

Any idea why? 

It seems that symbolColor is not a property of spark checkBox (if I start to type "s" in the mxml code, for example, there is no "symbolColor" property option displayed by Flash Builder)... but somehow it compiles and works. Why?

Where does symbolColor in the mxml code above connect to?

Thanks for any advice.