在同一应用程序中同一窗体只打开一个

        /// <summary>

        /// 在同一应用程序中同一窗体只打开一个

        /// </summary>

        /// <param name="frmOpen">要打开的窗体实例</param>

        /// <returns></returns>

        public static void OpenSeamForm(Form frmOpen)

        {

            foreach (Form frm in Application.OpenForms)

            {

                if (frm.Text == frmOpen.Text)

                {

                    frm.Visible = true;

                    frm.WindowState = FormWindowState.Normal;

                    frm.Activate();

                    return;

                }

            }

            frmOpen.Show();

        }