if(GETPOST('addline_predefined')||GETPOST('idprodfournprice'))// With combolist idprodfournprice is > 0 or -1. With autocomplete, idprodfournprice is > 0 or ''
if((GETPOST('addline_predefined')||GETPOST('idprodfournprice'))&&(GETPOST('pu')!==''))// With combolist idprodfournprice is > 0 or -1. With autocomplete, idprodfournprice is > 0 or ''