Thanks for the research!

It has been a very long time since I played with it, but I seem to remember some issues with :hover on MicroB, and settled for just a 'click' effect instead. I think it was something to do with the fact that there was a 'hidden' mouse pointer, so as you scrolled the list the wrong item would highlight. The 'hidden/virtual' mouse pointer would only change position on a press, so the area of the screen which you pressed last would show the hover effect when scrolling.