http://bugs.winehq.org/show_bug.cgi?id=17507
--- Comment #3 from Dylan Smith dylan.ah.smith@gmail.com 2009-02-24 11:26:32 --- (In reply to comment #2)
richedit: Fixed scrollbar visibility calculation after SetScrollInfo. (Bug 17507) http://www.winehq.org/pipermail/wine-patches/2009-February/069843.html
My patch that fixes the bug is in the git tree as commit 5f51221d9c1b94040ef354e7f62a0ce9a838cdab.
Please test and mark the bug as resolved if it works for you.