function popupcentro(url,nome,winwidth,winheight, scr){
	var altura	=	((screen.height/2) - (winheight/2));
	var largura	=	((screen.width/2) - (winwidth/2));
	window.open(url, nome, 'width = ' + winwidth + ',height = ' + winheight + ',scrollbars=' + scr + ', top = ' + altura + ', left = ' + largura);
}