https://bugs.winehq.org/show_bug.cgi?id=51429
--- Comment #3 from Zebediah Figura z.figura12@gmail.com --- All that message means is that a thread has been blocked on a critical section for more than 5 seconds. A critical section is a sleeping mutex, but generally shouldn't be held for long periods of time, and if it does, it's probably application misbehaviour. But the "?" means that it's one the application created (not Wine), so whatever the application is doing to hold on to that CS is probably its own fault. Not certainly, but probably, and given there's nothing visibly wrong, it's not worth investigating.
Most software in the Unix world is on a completely open-source stack, and is completely implemented at least according to its own specifications. As a result a log message either indicates a problem in the component itself, or in a higher or lower component, any of which deserve fixing. Wine is unique; we don't control the software that we run, and we can't fix its bugs. At the same time, large parts of Wine are simply not implemented, because no application has needed them yet. Hence it's very easy for applications to trigger ERR or FIXME messages meaning either that the application is doing something broken, or it's hitting a code path that isn't (fully) implemented in Wine. But often neither of these actually matter in practice. Hence we view log messages as a debugging aid—a FIXME *can* be harmless, or it can be the root cause of a failure—but not as a symptom of a bug in themselves (in most cases).