This is normal with Opera 10.5x and is an Opera bug. But help is on the way!
There are already a lot of threads about problems with that Opera version here — unfortunately only in German as it seems …
(My German post:
Opera 10.5 Testversion)
The Background:
Opera changed the whole Javascript engine with version 10.5x of their browser and thus that browser will not be recognised by the editor any more.
Since the changes are so large, we wheren't able to fix that without changing most parts of the editor, which seemed like a complete rewrite of the whole editor! That was the reason why the latest update was released, where we removed the Opera support for our editor completely, so that people where able to post again! You won't have any editor toolbar with that patch, but you can use all BBCodes by writing the codes manually. We decided to fix the rest of the Opera problems later, since there where too many of them …
As you can see, we have fixed a lot of problems with the editor since then in the version which is runnig in this board! But that version is not available publicly yet. We are currently testing it here (as always) and will be releasing it with one of the next updates.
A customer has posted our changes here (German post of user "rellek":
Opera 10.5 Testversion), you can try to edit the editor that way, but doing that is not recommended …
But while we where testing it here, we have been informed about that quoting problem and other problems still remaining in the editor. So we'll have to extend the update again and test it here before we can release ist to the public.
I hope that answeres the question for all english speaking customers.