@sutskn You need to remove and install the opera extension again. A little rough method but it is simple and the only one that I know of.

@rexneb Yes, but as we have already said in order to work this extension needs that the option in opera browser: "Warn on quitting Opera with multiple tabs open" must be disabled.

@nenadppx Yes ok, I'm using opera in Italian (like me)

@rosek97 I'm afraid it's not possible. At least I haven't found a way.

@rexneb: It is true it is a small bug, it happened to me too. But it is sufficient to disable in the options: "Warn before closing Opera with multiple tabs open" and it works fine.

I know what "SO" mean but my object was OPERA and I tried to make sense your answer. How I said, it was not the same thing. OS password could be not too strong but instead could be Browser Master Pw, moreover You could have to use single User Session (for many reason) in sharing position, so you can use Opera and other\s could be use Firefox or IE, also you don't take into consideration portable version.

My OS account? You mean Windows or Opera account? anyway this not the same thing, Opera fills stores passwords and does not require any action before, no matter if I am logged in my Opera account or not. Whoever opens Opera, in the same windows session, has access to all accounts. Firefox has got better point on it.

I would like a master password in Opera browser, like Firefox.
Is there an extension for it? Why developers don't implement such important feature like it?
Bye at all.