private void btn_saoluu_ItemClick(object sender, ItemClickEventArgs e)
{
frm_backup backup = new frm_backup();
pnl_main.Controls.Clear();
pnl_main.Controls.Add(backup);
}
private void backUpDataToolStripMenuItem_Click(object sender, EventArgs e)
{
frm_backup _b = new frm_backup();
_b.ShowDialog();
}