Seems like a bad idea....
I think the master password is a far better idea even if opera does encrypt the passwords.

I have just migrated from firefox to Opera. Somehow it has imported all my firefox passwords into the opera password manager but there is no option for a master password as there was in firefox. Apparently its supposed to be under the preference /security/advanced but its not there. I want to set it so that I have to use the master password once per session for security purposes.
My browser is Version: 47.0.2631.39 (PGO) -
however when i check for updates I get this message
An error occurred while checking for updates

Any help would be appreciated