http://bugs.winehq.org/show_bug.cgi?id=2057
--- Comment #20 from Dylan Smith dylan.ah.smith@gmail.com 2008-10-27 19:35:39 --- I looked at Arindal, and I can confirm the bug that you mentioned, however I can also confirm that it isn't a richedit issue. I used native riched20, riched32, msftedit on wine and the bug was still present.
The bug was also not present on Windows XP with native and Wine's riched20, riched32, and msftedit dlls.
Perhaps a separate issue should be open for this bug. I think it would be a user32 bug.
I did notice that calling InvalidateRect with a NULL rect causes the scrollbar to be redrawn in Windows XP but not in Wine. I am not sure if this is related, because InvalidateRect isn't being called by the program with a NULL rect, and the rectangle it gives seems to cover everything but the scrollbar.