Windows Forms: A modal form that gets opened/closed by the application rather than the user?

partial class MySustainedDialog : Form {
	public MySustainedDialog(string msg) {
		InitializeComponent();
		lbMessage.Text = msg;
	}
	public new void Show() {
		base.ShowDialog();
	}

	public new void Hide() {
		this.Close();
	}

}

public class MyNoConnectionDialog : INoConnectionDialog {
            private FakeSustainedDialog _dialog;
	public void Show() {
		var w = new BackgroundWorker();
		w.DoWork += delegate {
			_dialog = new MySustainedDialog("Connection Lost");
			_dialog.Show();
		};
		w.RunWorkerAsync();
	}

	public void Hide() {
		_dialog.Close();
	}
}

public new void Hide()
    {
        if (this.InvokeRequired)
        {
            this.BeginInvoke((MethodInvoker)delegate { this.Hide(); });
            return;
        }

        this.Close();
    }