private void vendaToolStripMenuItem_Click(object sender, EventArgs e)
        {
            frm_venda frm = new frm_venda();

            frm.Show();
            this.Visible = false;
        }
        private void btn_venda_Click(object sender, EventArgs e)
        {
            frm_venda frm = new frm_venda();

            frm.Show();
            this.Visible = false;
        }