MdiContainer

         /// <summary>
         /// 显示form
         /// </summary>
         /// <param name="form">要显示的form</param>
         /// <param name="canClose">是否将其他form关闭</param>
         private void ShowForm(Form form, bool canClose)
         {
             foreach (Form mdiChild in MdiChildren)
             {
                 bool b = mdiChild.GetType() == form.GetType();
                 if (b)
                 {
                     form.Close();
                     mdiChild.Focus();
                     return;
                 }
                 if (canClose)
                 {
                     mdiChild.Close();
                 }
             }
             form.MdiParent = this;
             form.ControlBox = false;
             form.WindowState = FormWindowState.Maximized;
             form.Show();
         }