 
 import flash.display.DisplayObject;
 import flash.display.DisplayObjectContainer;
+import flash.display.InteractiveObject;
 import flash.events.Event;
 import flash.events.EventDispatcher;
 

        // If reached the sandbox root of either then done.
        if (aParent == aSbRoot || bParent == bSbRoot)
            return 0;    
            
        var aNestLevel:int = (a is UIComponent) ? UIComponent(a).nestLevel : -1;
        var bNestLevel:int = (b is UIComponent) ? UIComponent(b).nestLevel : -1;


        
        radioButtons.push(instance);

		// Apply group indices in "tab order" or "breadth-first" order.
        radioButtons.sort(readOrderCompare);
        for (var i:int = 0; i < radioButtons.length; i++)
            radioButtons[i].indexNumber = i;
        
