anchor.diff:  
     SparkDialog get dialog => getUIElement("#$id");
     SparkModal get modalElement => dialog.getShadowDomElement("#modal");
  -  bool get opened => modalElement.opened;
  +  bool get functionallyOpened => modalElement.opened;
  +
  +  bool get visuallyOpened {
  +    CssStyleDeclaration style = modalElement.getComputedStyle();
  +    String opacity = style.opacity;
  +    String display = style.display;
  +    String visibility = style.visibility;
  +
  +    return int.parse(opacity) > 0 && display != "none" && visibility != "visible";
  +  }
  +
     List<SparkDialogButton> get buttons =>
         dialog.querySelectorAll("spark-dialog-button");
   
  
positive.code:   group('first run', () {
      test('ensure about dialog open', () {
        ModalUITester modalTester = new ModalUITester("aboutDialog");
        expect(modalTester.opened, true);
      });
  
      test('close dialog', () {
        ModalUITester modalTester = new ModalUITester("aboutDialog");
        modalTester.clickButton("done");
        expect(modalTester.opened, false);
      });
    });
  }
  
negative.code: 
  library spark.workspace_test;
  
  import 'dart:async';
  import 'dart:html';
  
  import 'package:spark_widgets/spark_dialog/spark_dialog.dart';
  