https://bugs.winehq.org/show_bug.cgi?id=41560
--- Comment #5 from Alistair Leslie-Hughes leslie_alistair@hotmail.com --- Updated the URL.
It doesn't use uxtheme.
From a very basic test, I changed SCROLL_RefreshScrollBar to just Invalidate
the control when EnableScrollBar was called. This fixed the problem but I have no idea on what other side effects it might have.