function pop(x,w,h) {
	var l = ( (window.screen.width  - w) / 2 );
	var t = ( (window.screen.height - h) / 2 );
    janelinha = window.open(x,'fundo','leftmargin=0,topmargin=0,marginheight=0,marginwidth=0,toolbar=no,location=no,directories=no,status=no,menubar=no,scrollbars=no,resizable=no,top='+t+',left='+l+',screenX='+l+',screenY='+t+',copyhistory=no,height='+h+',width='+w+'');
}
// onclick="pop('pagina.htm',100,300)"