var popUpWin=0;

function abre_pop(URLStr, left, top, width, height)

{

  if(popUpWin)

  {

    if(!popUpWin.closed) popUpWin.close();

  }
  var left = (screen.width/2) - width/2;
  var top = (screen.height/2) - height/2;
  popUpWin = open(URLStr, 'popUpWin', 'toolbar=no,location=no,directories=no,status=no,menubar=no,scrollbars=no,resizable=no,copyhistory=yes,width='+width+',height='+height+',left='+left+', top='+top+',screenX='+left+',screenY='+top+'');

}