private void buttonModify_Click(object sender, EventArgs e)
{
WindowItem modif = new WindowItem("", valItemName.Text, Convert.ToDouble(valPrice.Text), Convert.ToInt32(valQuantity.Text), valDescription.Text);
modif.ShowDialog();
}
private void buttonAdd_Click(object sender, EventArgs e)
{
WindowItem windowAdd = new WindowItem(this);
windowAdd.ShowDialog(this);
}