MDI Form detecting with a child form is added or removed

Question

Is there an event I can use to tell if a child form has been added or removed from the MDI parent?

Answer 1

private void closeToolStripMenuItem1_Click(object sender, EventArgs e)
    {
      List
 fm = this.MdiChildren.ToList();
        if(fm!=null && fm.Count>0)
        {
            foreach(Form lfm in fm)
            {
                lfm.Close();
            }
        }
    }