[Bug 46004] SimSig: scroll bars in Options window do not render

https://bugs.winehq.org/show_bug.cgi?id=46004

--- Comment #6 from Jacek Caban  ---
Thanks for the test case, it makes debugging much easier.

It looks like scroll functions are called on a window that is of its own class,
but has matching extra size and calls scrollbar's window proc. The attached
patch helps.

I suspected such use case could work and tested it before sending the original
patch. My testing showed that it doesn't work, but maybe I missed something. It
needs more testing.