prova così..

//pulsante
on (release) {
getURL("javascriptopUp()");
}

//html
<script language="javascript" type="text/javascript">
function popUp() {

/* begin configuration */
var url = "newpage.html";
var w = "500";
var h = "300";
var menu = "no";
var scroll = "no";
var tool = "no";
var location = "no";
var resize = "no";
/* end configuration */

var winl = (screen.width - w) / 2;
var wint = (screen.height - h) / 2;
winprops = 'width='+w+', height='+h+', top='+wint+', left='+winl+', menubar='+menu+', scrollbars='+scroll+', toolbar='+tool+', location='+location+', resizable='+resize+''
window.open(url, 'popup', winprops);
}
</script>