function centeredPopup(myurl, myname, mywidth, myheight, scroll) {
	var winl = (screen.width - mywidth) / 2;
	var wint = ((screen.height - myheight) / 2) - 20;
	winprops = 'height='+myheight+',width='+mywidth+',top='+wint+',left='+winl+',screenX'+winl+',screenY='+wint+',scrollbars='+scroll+',resizable=no,status=no'
	mywin = window.open(myurl, myname, winprops);
	if (parseInt(navigator.appVersion) >= 4) { mywin.window.focus(); }
}

function openPopup(url, lokatie) {
	if (lokatie == undefined) {
		lokatie = 0;
	}
	centeredPopup(url+'&lokatie='+lokatie, 'RZWEB', 700, 550, 'yes');
}