http://bugs.winehq.org/show_bug.cgi?id=20604
--- Comment #8 from Raymond superquad.vortex2@gmail.com 2011-08-11 20:02:45 CDT --- Writing to the Primary Buffer
You cannot specify the size of the primary buffer, and you must accept the returned size after the buffer is created. A primary buffer is typically very small, so if your application writes directly to this kind of buffer, it must write blocks of data at short intervals to prevent the previously written data from being replayed.