The problem with making it asymmetrical is that in the case of two toplevel tabs (as opposed to frame and child) determining who&#x27;s the &quot;parent&quot; and who&#x27;s the &quot;child&quot; is a lot more complicated.<p>&gt; If you&#x27;re suggesting it would be technically difficult, I&#x27;m extremely skeptical of that.<p>I think it&#x27;s technically difficult to establish parent&#x2F;child relationships between toplevel windows, given opener disowning and so forth.<p>That&#x27;s not even getting into the possible compat issues, of course, from the behavior change itself.