asociar el botón [X] de un formulario

[Betina232022]

ya quite el evento closed


y tengo asi:


private void salirToolStripMenuItem_Click(object sender, EventArgs e)
{

FrmSalir1 Salir1 = new FrmSalir1();
Salir1.BanSS = BanSP;
Salir1.Owner = this;
Salir1.ShowDialog();
}


private void Closing(object sender, FormClosingEventArgs e)
{

salirToolStripMenuItem_Click(null,null);
e.Cancel = false;


}

en FrmSalir1 pongo Application.Exit();