private void DeleteLineOnImage2Button_Click(object sender, EventArgs e)
        {
            if (listBox2.SelectedIndex == -1)
                return;
            int index = listBox2.SelectedIndex;
            lista2.RemoveAt(index);
            listBox2.Items.RemoveAt(index);
            pictureBox1.Image = originalImage2;
            ReDrawLines(lista2);
        }