private void btnUpdateTask_Click(object sender, RoutedEventArgs e)
        {
            var      task = projectTaskViewSource.View.CurrentItem as task;
            FormTask form = new FormTask(task, context);

            form.ShowDialog();
            projectTaskViewSource.View.Refresh();
        }
        private void btnNewTask_Click(object sender, RoutedEventArgs e)
        {
            var project = projectViewSource.View.CurrentItem as project;

            if (project == null)
            {
                MessageBox.Show("No project selected.");
                return;
            }
            FormTask form = new FormTask(project, context);

            form.ShowDialog();
            projectTaskViewSource.View.Refresh();
        }