private void button1_Click(object sender, EventArgs e)
        {
            FrmDetailProductCategory productCategory = new FrmDetailProductCategory();

            productCategory.MdiParent = this.MdiParent;
            productCategory.Show();
            this.Close();
        }
 private void button3_Click(object sender, EventArgs e)
 {
     if (dgvProductCategory.SelectedRows.Count > 0)
     {
         var id = (int)dgvProductCategory.SelectedRows[0].Cells["ID"].Value;
         FrmDetailProductCategory detailBuyer = new FrmDetailProductCategory();
         detailBuyer.SetProductCategory(id);
         detailBuyer.Show();
         this.Close();
     }
 }