private void delete_btn_Click(object sender, RoutedEventArgs e)
{
TaskModel delete_task = list_tasks_grid.SelectedItem as TaskModel;
if (delete_task != null)
{
ListController controller = new ListController();
bool result = controller.DeleteTask(delete_task.Task_id);
if (result)
{
tasks_list.Remove(delete_task);
}
}
}