The current snapshot for Opera 12.12 comes almost two weeks after the previous one. As usual, it is a development build so glitches and quirks are expected.
The fixes available in this release address stability issues as well as functionality problems. Some crash bugs have been eliminated and deleting private data should no longer remove persistent storage by default, which also included extension data; in this revision deleting data from extensions is available as a separate option.
Additional repairs touch on the title bar of the main window, which turned black after hibernation and the buttons for closing minimizing and maximizing the window would no longer be available.
Also fixed is the problem with alpha transparency drawing artifacts, which would show up with hardware acceleration turned on. The full list of changes can be viewed here.