how am I responsible for the security of B at all?
Mozilla has been very vocal about sharing these things between browser vendors in the past, so one would expect them to follow up themselves on what they ask of others.
There is NOTHING in there about Opera's susceptibility.
It would be naive to think that evildoers wouldn't test holes in one browser in other browsers as well.
I bet "I" could find and fix known security problems in larger software products in a day, too.
There's a difference between creating an actual fix, and deploying the fix in a finished, tested version. This post has a bit more detail on that.
Slashdot Mirror
Mozilla can release its own fix and still hold back on the details until the other browser vendors have been able to release their fixes.