function popup(width,height) {
width=width+20;
height=height+30;
new_window = window.open('','popup','width=' + width + ',height='
+ height + ', left=' + Math.round((screen.width - width)/2) + ',top='
+ Math.round((screen.height - height)/4) +
',location=0,status=0,menubar=0,toolbar=0,scrollbars=0,resizable=0');
}