private void đổiMậtKhẩuToolStripMenuItem_Click(object sender, EventArgs e)
{
DoiMatKhau doiMatKhau = new DoiMatKhau();
doiMatKhau.MdiParent = this;
doiMatKhau.Show();
LayoutMdi(MdiLayout.TileVertical);
}
private void btndoimatkhau_Click(object sender, EventArgs e)
{
DoiMatKhau dmk = new DoiMatKhau(TenDangNhap);
dmk.ShowDialog();
}