I want a .txt page to be opened in a new tab when the .swf file opened. IE blocks it.
The .swf will be called from an external web page. Therefore, I cannot add more code there.
I'm not much experienced with AS and tried adding different codes in the timeline. navigateToURL with "parent" works to open in the same page but can't get it to open in new tab, with "_blank".
This target="" attribute on an anchor is depreciated. It is invalid markup. The reason why is it is decidedly the "users" decision to open content in a new window or a new tab, no longer yours. You can open child windows via javascript which are then owned by the parent window and allowed (aside popup blockers).
The only way I've found that validates and opens a new window, yet is probably going to be fixed, is intercepting an anchor link such as:
<a href="http://www.adobe.com" onclick="target='_blank';">Open adobe in a new tab or window (based on browser preferences)</a>
However you said you do not have access to the code on the page the SWF lands on? If that's the case then you simply can't do what you want from inside a SWF alone. You can't make an anchor or write any custom JavaScript to work with ExternalInterface so you can't do it.
North America
Europe, Middle East and Africa
Asia Pacific