private void btnEditPresentation_Click(object sender, RoutedEventArgs e)
        {
            var view = new PresentationView();
            var presentationViewModel = (PresentationViewModel)((Button)sender).DataContext;

            presentationViewModel.Mode = Mode.Edit;
            view.DataContext           = presentationViewModel;
            view.ShowDialog();
        }
        private void btnAddPresentation_Click(object sender, RoutedEventArgs e)
        {
            var view = new PresentationView();
            var presentationViewModel = new PresentationViewModel()
            {
                Researcher = (ResearcherViewModel)DataContext,
                Mode       = Mode.Add
            };

            view.DataContext = presentationViewModel;
            view.ShowDialog();
        }