How to set focus to child and opener windows when tabbed

What exactly do you want to achieve? To set the focus inside the other window to the first link / button / form field / whatever? Or to make the other window (browser tab) the active browser tab?

Anyways - maybe the opener.focus() call doesn't work because both windows are not served from the same origin. Try setting up a communication channel via postMessage to resolve this. So in the opener document, listen for an event like this:

window.addEventListener('message', function (event) {
    window.focus();
}, false);

And in the opened window, send the message like this:

opener.postMessage('foo', '*');

Sadly, I can't test if this is working right now. (I guess it should, though...)

A few things to add, though:

1. Some legacy crap browsers don't support postMessage (see caniuse.com). There are workarounds, though. :)
2. I used the W3 standard notation for attaching the event listener. IE8 and below use their proprietary attachEvent equivalent.
3. You should replace the '*' origin wildcard with the actual origin of the opener window.
4. In the message event listener function, you should inspect event.origin and only run your actual payload if the origin is correct.