Lock a previous form when opening a new one

Question

There I have a button_click event and when it happens it opens a new Form. How do I lock the principal Form, so that it can't be looked at or changed until new Form is closed?

Here's my event handler:

  private void button4_Click(object sender, EventArgs e)
  {
      Form2 f = new Form2();
      f.Show();
  }

Answer 1

Try showing the child form as a modal window:

Form2 f = new Form2();
f.ShowDialog();