     }
     
     /**
+     *  Default border alpha. If NaN, don't change alpha value.
+     * 
+     *  @default NaN 
+     *  
+     *  @langversion 3.0
+     *  @playerversion Flash 10
+     *  @playerversion AIR 1.5
+     *  @productversion Flex 4
+     */
+    protected function get defaultBorderAlpha():Number
+    {
+        return NaN;
+    }
+    
+    /**
      *  @private
      */
     override protected function updateDisplayList(unscaledWidth:Number, unscaledHeight:Number):void

            var isError:Boolean = false;
            var borderItemColor:uint;
            var errorColor:uint = getStyle("errorColor");
            
            if (getStyle("borderColor") == errorColor)
                borderItemColor = errorColor;

            for (var i:int = 0; i < borderItems.length; i++)
            {
                if (this[borderItems[i]])
                {
                    this[borderItems[i]].color = borderItemColor;
                    if (!isNaN(borderAlpha))
                        this[borderItems[i]].alpha = borderAlpha;
                }
            }
        }

