Hi Dave,
The functionality to scroll up top is coded in less than 10 minutes, the whole hover menu not. In general, In TW2 I found the hover menu to be mostly clutter. In other words, it was neat, but I never really used it as it was.
However, while not the answer you were asking for: unless you're on a tablet: HOME / POS1 on your keyboard will do. On a tablet, a generous swipe should do as well. Also, remember the open list in the sidebar, that's possibly a better way to scroll to the tiddler of interest. Other than that, you may want to look into making a sticky header that is always visible, if you need this for some main navigation.
Best wishes,
Tobias.