PhotoFiltre 7.2.1 problems with a vertical scrollbar

reactOS 0.4.6RC1
The issue is quite old, personally I know it since at least 0.4.0rls.

Affected is the scrollbar to the right.
It scrolls very jerky (elements do jump forth and back and not all elements do scroll)
see 0.4.6RC1-PhotoFiltre7.2.1-scrolling.webm

(The vertical scrollbar eventually should not be visible at all in default resolution, cause everything would fit into the GUI element even without the bar.)???

ros logs nothing during this scenario.