Hints needed for riched20/scroll bug solving

[Paul Vriens]

Hi,

When starting the Zoo Tycoon 1 demo for the first time, the license
agreement appears. I know that nobody reads this ;-) but hey. When I
click in the scrollbar (page down) the page goes down 1 page and the
scrollbar changes. When I however click the down-arrow in the scrollbar,
the page goes down (2 lines) but the scrollbar doesn't change.

Who/what is responsible for this scrollbar? I've tried (extra) tracing
for riched20 and scroll but nothing so far.

Cheers,

Paul.