private void btPhieuBao_Click(object sender, EventArgs e)
        {
            frmQuanLyPhieuBao fPB = new frmQuanLyPhieuBao();

            fPB.Show();
            Close();
        }
        private void button2_Click(object sender, EventArgs e)
        {
            frmQuanLyPhieuBao frmQLPB = new frmQuanLyPhieuBao();

            frmQLPB.Show();
            Close();
        }