// popup na srodku ekranu
function popup(url, w, h) {
	if (screen.availHeight) {
		var left = (screen.availWidth - w) / 2;
		var top = (screen.availHeight - h) / 2;
	} else {
		var left = (screen.width - w) / 2;
		var top = (screen.height - h) / 2;
	}

	if (left < 0) left = 30;
	if (top < 0) top = 30;
	
	window.open(url,'', 'width='+ w +',height='+h+',top='+top+',left='+left
		+',resizable=yes,scrollbars=yes');
	return false;
}