I replaced the 2-button PS/2 mouses on a few PCs with my favoured type of
wheely-scrolly Logitech ones.
I ran mouseconfig and told it that I had a MouseMan+/FirstMouse+, which is
roughly what they are. It offered to update XF86Config, and I agreed that
that might be a good idea.
But, while I could paste with the middle button, I couldn't scroll in
gnome-terminals, as no ZAxisMapping line had been added to the "Pointer"
section of XF86Config.
This is fixed in the next release... (and pinstripe)