Hi Steven! Thanks for your reply!
In my Win7 install (which I thought was an MBv3 from a few months ago, but I could be wrong!), middle-click brought up the on-screen cursor (as in every other software Eg. Chrome), and moving the mouse scrolled the list in that direction. Staying near the centre was a slow scroll, and moving to the edge of the screen could make it scroll very fast. I could get to the bottom of a long list of music very quickly.
Right now, I can only scroll through a list by rotating the mouse wheel or grabbing the scrollbar. With long lists, the former is too slow, and the latter is too fast/sensitive when trying to zero in on an artist or album.
So you're saying that this was a design decision, and not a Win10 bug? If so, that's ok. I'll get used to it!