private void btnEditGrade_Click(object sender, RoutedEventArgs e)
        {
            var grade  = dgvGrades.SelectedValue as GradeViewModel;
            var rights = UserViewModel.CurrentUser.CanEdit(grade);

            if (RightsEnum.Success != UserViewModel.CurrentUser.CanEdit(grade))
            {
                MessageBox.Show("User can not edit this grade at this stage.");
                return;
            }
            var window = new EditGradeWindow(_student.Name, grade);

            window.ShowDialog();
            RefreshMarks();
        }
 private void btnEditGrade_Click(object sender, RoutedEventArgs e)
 {
     var grade = dgvGrades.SelectedValue as GradeViewModel;
     var rights = UserViewModel.CurrentUser.CanEdit(grade);
     if (RightsEnum.Success != UserViewModel.CurrentUser.CanEdit(grade))
     {
         MessageBox.Show("User can not edit this grade at this stage.");
         return;
     }
     var window = new EditGradeWindow(_student.Name, grade);
     window.ShowDialog();
     RefreshMarks();
 }