void EditClick(object sender, EventArgs e)
        {
            GF.selected_id = Convert.ToInt32(btn_dgv.DGV.SelectedRows[0].Cells["item_price_id"].Value);

            using (selling_price_manage managePage = new selling_price_manage())
            {
                managePage.Owner           = this;
                managePage.manage_btn.Text = "UPDATE";
                managePage.Text            = "EDIT ITEM PRICE";

                managePage.ShowDialog();
            }
        }
        // DELEGATE PART :: BEGIN
        void AddClick(object sender, EventArgs e)
        {
            GF.selected_id = 0;

            using (selling_price_manage managePage = new selling_price_manage())
            {
                managePage.Owner           = this;
                managePage.manage_btn.Text = "ADD";
                managePage.Text            = "ADD ITEM PRICE";

                managePage.ShowDialog();
            }
        }