Reset scroll offset on item change

[eth0net]

Scroll offset needs resetting when the item is changed, or at least capped to the max offset.

If you scroll down a long list, then change the item to something with a shorter list, you can end up with an empty list as the offset is now higher than the list length.

Resetting the scrollOffset to 0 may be the best default, as it's an easy to understand behaviour, though this could be made configurable in the future.