Illustrator SDK :: Close Button (X) On UI Extension

I am very new to Flex/Flash/Illustrator. Using Illustrator CS5.1, Flex 3.6 SDK in Flash Builder 4.5, and Visual Studio 2010.I am developing a hybrid plugin for Adobe Illustrator.  The plugin is C++ and interfaces with a hardware device and an UI extension built on Flex/Flash.  It uses the CSXS library (version 2.0 based on Flex 3.4 SDK) to perform the communication between the extension and the plugin.
 
When the UI extension closes, I need the plugin to perform some tasks. These tasks might be related to Illustrator and/or to the device it communicates with. If the UI is closed using a button I add to the UI, the plugin runs the tasks as needed.  If the UI is closed using the 'X' button in the corner of the window, I can not get the CSXS interface dispatch events to carry over to the plugin.  This is the same dispatch events used from the UI button that I manually created and works fine.
 
I have tried capturing the exiting event from the NativeApplication and I do see myself entering the associated function to that capture.  The dispatch events run but I do not enter the corresponding functions in the plugin.Below is one of several attempts at making this work (believe this was found on the Adobe forums):
 
public function init() : void
{
      NativeApplication.nativeApplication.addEventListener(Event.EXITING, windowedapplication1_closingHandler);
} 
protected function windowedapplication1_closingHandler(event:Event):void
{
      event.preventDefault();
      //event.stopImmediatePropagation();
      CSXSInterface.getInstance().dispatchEvent(new CSXSEvent("com.testui.events.closing", CSXSEventScope.APPLICATION));
}
 
Again, windowedapplication1_closingHandler will process but the dispatched event is not seen by my plugin (when the 'X' is clicked).Is there a way to disable/hide the 'X' in the corner of the window?Am I not properly "capturing" and "halting" the exit event?Should I move away from the CSXS Library and use sockets to perform this communication (though the closing of the extension may have the same affect on the socket communication)?I am currently working on Windows 7 64-bit (if that matters) but the plugin will have to work on Mac too.