function abreMapa(){
	Wwidth  = 539;
	Wheight = 409;

	tamW = screen.width;
	tamH = screen.height;

	posW = (tamW/2) - (Wwidth/2);
	posH = (tamH/2) - (Wheight/2);

	params = ",left="+posW+",top="+posH+",width="+Wwidth+",height="+Wheight+",toolbar=0,menubar=0,scrollbars=0,status=0";

	window.open('mapa.htm','mapa',params);
}