         // If reached the sandbox root of either then done.
         if (aParent == aSbRoot || bParent == bSbRoot)
             return 0;    
-            
+		
+		// first check to see if we can compare by tabIndex
+		var aTabIndex:int = (a is InteractiveObject) ? InteractiveObject(a).tabIndex : -1;
+		var bTabIndex:int = (b is InteractiveObject) ? InteractiveObject(b).tabIndex : -1;
+		
+		// if one of the items being compared has a defined tabIndex, compare by tabIndex
+		if(aTabIndex > -1 || bTabIndex > -1)
+		{
+			if (aTabIndex > bTabIndex)
+				return (bTabIndex == -1) ? -1 : 1; // items with assigned tabIndex come before those without
+			if (aTabIndex < bTabIndex)
+				return (aTabIndex == -1) ? 1 : -1; // items without assigned tabIndex come after those without
+			if (a == b)
+				return 0;
+		}
+
+		// if neither item has a defined tabIndex, compare by "breadthOrder"
         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 "breadth-first" order.
        radioButtons.sort(breadthOrderCompare);
        for (var i:int = 0; i < radioButtons.length; i++)
            radioButtons[i].indexNumber = i;
        

        else if (a == b)
            return 0;
        else // Nest levels are identical, compare ancestors.
            return readOrderCompare(aParent, bParent);
    }

    //--------------------------------------------------------------------------
