void dadi_FormClosed(object sender, FormClosedEventArgs e) { dadi = null; }
private void deleteADepartmentToolStripMenuItem_Click(object sender, EventArgs e) { if (dadi == null) { dadi = new DeleteAnDepartmentInfo(); dadi.MdiParent = this; dadi.FormClosed += dadi_FormClosed; dadi.Show(); } else { dadi.Activate(); } }