private void button4_Click(object sender, EventArgs e)
{
ql_dancu frm = new ql_dancu();
frm.ShowDialog();
frm.Hide();
}
private void bnKho_Paint(object sender, PaintEventArgs e)
{
ql_dancu frm = new ql_dancu();
//frm.ShowDialog();
// this.Hide();
}