      *  Storage for errorString property.
      */
     mx_internal var _errorString:String = "";
+    
+    /**
+     *  @private
+     *  Storage for previous errorString property.
+     */
+    private var oldErrorString:String = "";
 
     /**
      *  @private

     */
    public function set errorString(value:String):void
    {
        var oldValue:String = _errorString;
        _errorString = value;

        var showErrorTip:Boolean = getStyle("showErrorTip");
        
        if (showErrorTip)
            ToolTipManager.registerErrorString(this, oldValue, value);

        errorStringChanged = true;
        invalidateProperties();

        if (errorStringChanged)
        {
            errorStringChanged = false;
                        
            if (getStyle("showErrorTip"))
                ToolTipManager.registerErrorString(this, oldErrorString, errorString);
            
            setBorderColorForErrorString();
        }

        if (blendModeChanged)
        {
            blendModeChanged = false; 
