I tried with the patch from
CORE-17780 and that fixed this bug for the rapps treeview,
unfortunately that scrollbars theming glitch is still present for a RichEdit, e.g. as it is used by RosBE setup.
Tro reproduce just enable the Lunar theme and then try the RosBE setup, then try to scroll that RichEdit control with the scrollwheel. It will draw the scrollbar unthemed erroneously.
The log is uninteresting.
Can we apply a similar workaround for this case as we did for