>>>>> Ikumi Keita <ikumi@ikumi.que.jp> writes:
> I think the behavior of the above item 1 is a bug. When f-l-e-r-b-q
> cannot find a matching opening quote, it should just give up to extend
> the region anymore.

After reconsideration, I realized that such giving up is not appropriate
when that unmatched close quote has, in front of it, other open-close
quote pairs. Examples:
      abc ``def ghi'' jkl $y''=x^{2}$
      abc <<def ghi>> jkl $y''=x^{2}$

So the correct way is to continue searching backwards another close
quote, I think. The revised patch is attached. I'll install it soon.

Regards,
Ikumi Keita