public F_filhoCheckBox()
        {
            InitializeComponent();

            try
            {
                fcb = Application.OpenForms["F_checkBox"] as F_checkBox;

                cb_carro.Checked  = fcb.cb_carro.Checked;
                cb_aviao.Checked  = fcb.cb_aviao.Checked;
                cb_navio.Checked  = fcb.cb_navio.Checked;
                cb_onibus.Checked = fcb.cb_onibus.Checked;
            } catch
            {
                MessageBox.Show("erro ao abrir formulário");
            }
        }
        private void checkBoxToolStripMenuItem_Click(object sender, EventArgs e)
        {
            F_checkBox f_checkbox = new F_checkBox();

            f_checkbox.ShowDialog();
        }