The command you're looking for is
navigateToURL(request:URLRequest, "_blank"):void
"_blank" specifies a new window.
You want to load them from a textfile, but this is just not possible from Flash because Flash does not allow disk access.
Unless you mean the textfile is hosted on a server.
EDIT: Here is a comprehensive overview of loading external data into Flash: Adobe Help
var data:Object;
// Load the external file at startup.
// Variables will be loaded and can be referenced directly.
// The request by default can only call files on the server hosting the Flash.
private function onInitializationComplete(event:Event):void
{
var loader:URLLoader = new URLLoader();
var request:URLRequest = new URLRequest("externalFile.txt");
loader.addEventListener(Event.COMPLETE, completeHandler);
loader.dataFormat=URLLoaderFormat.VARIABLES; // Change to .TEXT if you want to parse it yourself.
loader.load(request);
}
private function completeHandler(event:Event):void
{
data = event.target.data;
}
private function onClickHandler(event:MouseEvent):void
{
var bitmapName:String = (event.target as Sprite).name; // Get the name of the bitmap clicked.
var URL:String = data[bitmapName]; // A variable with bitmapName should have been loaded from the text file, so I am calling it by name.
var openMethod:String = data[bitmapName + "Method"];
navigateToURL(URL, openMethod);
}
Text file should contain data like this:
bitmap1=www.google.com&bitmap1Method=_blank&bitmap2=www.amazon.com&bitmap2Method=_self
If you want to