Missing vertical scrollbar in spektrum aspect

Wavelab Pro 9.0.10 (build 536) 64 bit

When I switch from waveform to spektrum aspect, I miss the scrollbar for
vertical slide of the spektrum. There are only two arrows without function.

There is one if you choose the linear frequency scale, and if you zoom.
With the logarithmic scale, no scroll bar.

Ok, I see, thank you.