function popup(n,l,h)
{
// n = page 
// l = width
// h = height
   l=l+20;
   h=h+20;   
    xpos = (screen.width - l ) / 2
    ypos = (screen.height - h) / 2
window.open(n,"","width="+l+",height="+h+",left="+xpos+",top="+ypos+",resizable=no,scrollbars=auto,menubar=no,toolbar=no,directories=no,location=no,status=no")
}