My point was that window.opener can be nulled out.
> I'm also skeptical of legitimate uses for controlling the location of another top level window as well
Happens all the time: open a popup, then navigate it to places. Not on web pages much nowadays, though it was more common in the past, but in various intranet apps? All the time.
I'm sure it can. That does not mean the browser needs to forget it. The parent/child relationship of browser windows is not some massive technological feat.
That something is used does not mean it is legitimate. I am not disputing that it is used. I am not saying I think they'll fix it. I am questioning the validity of the decision to allow it in the first place. I have no doubt that other means would be found to achieve the same end goals if it were not available.
> That something is used does not mean it is legitimate.
While I agree, in practice what this means is that either all browsers need to coordinate rollout precisely (and even then the result will be that many users just stay on insecure versions of browsers instead of updating) or you will have pages (or employers) telling users to switch to whatever browser lags in rolling this out.
We've seen this play out before. The result is that you end up with users picking whichever browser defects (which reduces the incentive for other browsers to do this) or being stuck on the equivalent of IE6.
The benefit of changes that do NOT break compat is that browsers can just roll them out without needing to worry about the above side-effects.
> I'm also skeptical of legitimate uses for controlling the location of another top level window as well
Happens all the time: open a popup, then navigate it to places. Not on web pages much nowadays, though it was more common in the past, but in various intranet apps? All the time.