function popuplink(url,windowname,width,height,toolbar,scrollbars,menubar,toolbar,
                                  resizable,location,directories,status) {

  width>0?width:screen.width/3;
  height>0?height:screen.height/3;

  var screenX = (screen.width/2 - width/2);
  var screenY = (screen.height/2 - height/2);

  var features= "width=" + width + ",height=" + height;
  features += ",screenX=" + screenX + ",left=" + screenX;
  features += ",screenY=" + screenY  +",top=" + screenY;
  features += ",toolbar=" + toolbar +",scrollbars="+scrollbars;
  features += ",menubar="+menubar+",resizable=" + resizable;
  features += ",location=" + location +",directories="+directories;
  features += ",status=" + status;

  var mywin = window.open(url,'popup',features);

  if (mywin) mywin.focus();

  return mywin;
}