You can change the source code of your page to allow a scrollbar at lower resolutions:
<frame name="up" src="onlinestore/navigation.html" scrolling="no">
<frame name="down" src="onlinestore/start.html">
The frame “down” contains the WPF.
If you enable scrolling in this frame, then the whole WPF is scrollable.
A second possibility is to reduce the size of the WPF using the FRONTEND.HEIGHT parameter.
Now the inside of the WPF is scrollable.