var win = null;
function popup(mypage,myname,w,h,scroll){
 LeftPosition = (screen.width)?(screen.width-w)/2 : 0;
 TopPosition = (screen.height)?(screen.height-h)/2 : 0;
 settings = 'height='+h+',width='+w+',top='+TopPosition+',left='+LeftPosition+',scrollbars='+scroll+',resizable,directories,location,menubar,status,toolbar';
 win = window.open(mypage,myname,settings);
}