private void btn_Venda_Click(object sender, EventArgs e)
        {
            foreach (Form form in Application.OpenForms)
            {
                if (form.GetType() == typeof(frmVendas))
                {
                    form.Activate();
                    return;
                }
            }

            Form newForm = new frmVendas();
            newForm.MdiParent = this;
            newForm.Show();

            //frmVendas venda = new frmVendas();
            //venda.MdiParent = this;
            //venda.Show();
        }
        private void btn_VendasProdutos_Click(object sender, EventArgs e)
        {
            try
            {
                frmVendas formVendas = new frmVendas();
                formVendas.MdiParent = this;
                formVendas.Show();
            }
            catch (Exception Erro)
            {

                MessageBox.Show("Erro Ao Chamar O Formulario: " + Erro.Message, "Erro");
            }
        }