The latest release builds of Opera for the Mac are atrocious, crashing all the time. All. The. Fucking. Time. And with seemingly random user interactions leading up to the crash, which kind of suggests a race condition, memory allocator or some other effectively random bug, although I have so many damn tabs open, many of which have JS stuff going on in the background, that it's hard to tell.
Another thing which makes it even harder to tell, is the rubbish stack trace provided when it crashes. A major downside to having closed-source software like Opera is that you can neither properly investigate these crashes nor solve them properly. Why not provide at least some kind of assertions or at least filename/line numbering in the stack traces? AFAIK, adding that sort of debug info, even for a shitty language like C++, isn't that big of a performance hit.
And if they're purposely obscuring debug info because Opera is closed source, then WHAT THE FUCK. Nothing "damaging" would be leaked by such information. Blargh!