private void رقمالفاتورةToolStripMenuItem_Click(object sender, EventArgs e)
{
if (addBill == null)
{
addBill = new add_bill();
addBill.MdiParent = this;
addBill.FormClosed += new FormClosedEventHandler(addBill_FormClosed);
addBill.Show();
}
else
{
addBill.Activate();
}
}
void addBill_FormClosed(object sender, FormClosedEventArgs e)
{
addBill = null;
//throw new NotImplementedException();
}
