private void DeleteTestCase(object sender, RoutedEventArgs e)
        {
            TestCaseProxy testCaseToDelete = ((MenuItem)sender).DataContext as TestCaseProxy;
            TestManager manager = new TestManager();
            manager.DeleteById(testCaseToDelete.Id);

            ProjectProxy projectProxy = this.UIProjectProxyList.Where(proj => proj.Areas.Any(a => a.ID == testCaseToDelete.AreaID)).FirstOrDefault();
            if (projectProxy != null)
            {
                AreaProxy areaProxy = projectProxy.Areas.Where(a => a.ID == testCaseToDelete.AreaID).FirstOrDefault();
                if (areaProxy != null)
                {
                    areaProxy.TestCasesList.Remove(testCaseToDelete);
                    this.SetCurrentTestCase(new TestCaseProxy());
                }
            }
        }