//Cancel Sales Invoice private void διόρθωσηToolStripMenuItem4_Click(object sender, EventArgs e) { cancelSalesInv = new CancelSalesInvoice(); mainMessage.Text = "Ακύρωση τιμολογίου Πώλησης Σε εξέλιξη......"; cancelSalesInv.MdiParent = this; cancelSalesInv.Show(); cancelSalesInv.FormClosing += new FormClosingEventHandler(cancelSalesInv_FormClosing); }