We had a feeling that Opera 12.12 would roll out before Christmas and today the Norwegian developer delivered the stable version. The new build focuses on improving stability and security of the browser, no new significant features are available.
Opera 12.12 introduces the possibility to delete settings and data from extensions separately in the Delete Private Data dialog (option turned off by default). The reason behind this change is that deleting private data would also purge persistent storage, which included extension data.
The 'Delete Private Data' dialog has been modified to become more usable on smaller screens as well.
Users should no longer have problems with the browser’s interface at startup after previously closing it while in full-screen.
Security-wise, the developer solved a problem with malformed GIFs that could allow execution of arbitrary code. Another problem solved consisted in the fact that repeated attempts to access a target site could trigger address field spoofing.
On UNIX systems private data could be revealed to other computer users, or even modified by them; this hole has been plugged.