private void button1_Click(object sender, EventArgs e)
        {
            Person         p        = new Person();
            EditPersonForm editForm = new EditPersonForm(p);

            if (editForm.ShowDialog() != DialogResult.OK)
            {
                return;
            }

            pers.Add(p);


            personsListView.VirtualListSize = pers.Count;
            personsListView.Invalidate();
        }
        private void button2_Click(object sender, EventArgs e)
        {
            if (personsListView.SelectedIndices.Count == 0)
            {
                return;
            }

            Person p = pers[personsListView.SelectedIndices[0]];

            //ListViewItem item = personsListView.SelectedItems[0];

            EditPersonForm editForm = new EditPersonForm(p);

            if (editForm.ShowDialog() == DialogResult.OK)
            {
                personsListView.Invalidate();
            }
        }