This examples shows how open HTML Java Script POPUP from Action Script

button.addEventListener(MouseEvent.MOUSE_DOWN, onClick);

function onClick(e:MouseEvent):void {
 var jscommand:String = "window.open('http://www.google.com','win', 'width=300,height=400,toolbar=no,scrollbars=yes');";
 var url:URLRequest = new URLRequest("javascript:" + jscommand + " void(0);");
 navigateToURL(url, "_self");
}