var top, left;
function popup (url, nome, w, h, scrollbars, center) {
    top = (center == 1) ? Math.ceil((screen.height-h)/2) : 0;
    left = (center == 1) ? Math.ceil((screen.width-w)/2) : 0;
    janela = window.open(url, nome, "scrollbars=" +scrollbars+ ",width=" +w+ ",height=" +h+ ",top=" +top+ ",left=" +left);
    janela.focus();
}
function mostramoedas() {
	if (document.getElementById('moedas').options[document.getElementById('moedas').selectedIndex].value != "0")
		popup (document.getElementById('moedas').options[document.getElementById('moedas').selectedIndex].value, 'popmoeda', 268, 215, 0, 1);
}