private void btnAddTask_Click(object sender, RoutedEventArgs e)
        {
            TermOverviewWindow termWindow = new TermOverviewWindow(TermOverviewWindow.OPERATION_ADD, null); //Вывозов окна добавления задачи

            if (termWindow.ShowDialog() == true)
            {
                updatedgOverview(null); //обновляем dgOverview
            }
        }
        private void dgOverview_MouseDoubleClick(object sender, MouseButtonEventArgs e)
        {
            if (dgOverview.SelectedItem != null)
            {
                Term selectedTerm = dgOverview.SelectedItem as Term;

                int termID = Convert.ToInt32(selectedTerm.termID);

                if (termID > -1)
                {
                    TermOverviewWindow termWindow = new TermOverviewWindow(TermOverviewWindow.OPERATION_EDIT, selectedTerm); //Вывозов окна добавления задачи

                    if (termWindow.ShowDialog() == true)
                    {
                        updatedgOverview(null); //обновляем dgOverview
                    }
                }
            }
        }