function Popup(URL, Width, Height)
{
  var w, h, l, t, s; s = "";
  if(Width<screen.availWidth-20)
    w = Width;
  else
  {
    s = ",scrollbars=yes";
    w = screen.availWidth-20;
  }
  l = Math.round((screen.availWidth-w)/2)-5;
  if(Height<screen.availHeight-40)
    h = Height;
  else
  {
    s = ",scrollbars=yes";
    h = screen.availHeight-40;
  }
  t = Math.round((screen.availHeight-h)/2)-15;
  var locstr = PopupURLPrefix+URL;
  w=window.open(locstr,"Popup","width="+w+",height="+h+",left="+l+",top="+t+",status=no,toolbar=no,menubar=no,location=no"+s);
  w.focus();
  return false;
};