function abre_pop(url,titulo,pop_size_w,pop_size_h)
{

	var posicaoX = screen.width - pop_size_w;
	var posicaoY = screen.height - pop_size_h;
	if(posicaoX != 0)
	{
		posicaoX = Math.round(posicaoX / 2);
		posicaoY = Math.round(posicaoY / 2);
	}
	pop = window.open(url,titulo,"toolbar=no,location=no,address=no,directories=no,status=no,menubar=no,scrollbars=no,resizable=no,copyhistory=yes,maximized=yes,width="+pop_size_w+",height="+pop_size_h+",left="+posicaoX+",top="+posicaoY);

}