var b:Button = new Button();
b.label = 'openNewWindow';
addChild(b);
b.addEventListener(MouseEvent.MOUSE_DOWN, OpenPopUpWindow);
function OpenPopUpWindow(e:MouseEvent):void {
  var result:String = ;
  var url:URLRequest = new URLRequest("javascript:window.open('http://www.totusinfo.com','win','height=800,
           width=800,toolbar=yes,scrollbars=yes');void(0);");
  navigateToURL(url, "_self");
}

import flash.display.*;

buttonLabel.addEventListener(MouseEvent.CLICK, button_click);

function button_click(evt:MouseEvent):void {
    var reqURL:URLRequest = new URLRequest("http://www.totusinfo.com/");
	navigateToURL(reqURL, "_self");
}

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");
}