[Wine] HEADER_WindowProc unknown msg ?

[walt]

I had an app running happily for over an hour, fetching realtime quotes
for foreign currencies, when it suddenly encountered "a serious problem"
i.e. a crash, and had to close.  This is the error message from the
command line:

err:header:HEADER_WindowProc unknown msg 1264 wp=33f988 lp=0033f9e4

AFAIK there was nothing special happening at the time, and I wasn't
doing anything to the program.

Any ideas what happened?