private void modificarToolStripMenuItem_Click(object sender, EventArgs e) { if (modificar == null) { modificar = new ModificarTweet(negocio); modificar.MdiParent = this; modificar.Dock = DockStyle.Fill; modificar.FormClosed += new FormClosedEventHandler(cerrarModicar); modificar.Show(); } else { modificar.Activate(); } }