function show(el) { document.all[el].style.visibility = 'visible'; }
function hide(el) { document.all[el].style.visibility = 'hidden'; }

function openwin(link, scroll, width, height)
{
  str = '"menubar=no,';
  if (scroll == "yes") str += ' scrollbars=yes,';
  str += ' width=' + width + ', height=' + height + '"';
  win = window.open(link, "", str);
  win.moveTo(screen.availWidth/2 - width/2, screen.availHeight/2 - height/2);
}