Comment # 2 on bug 1027349 from Alex Armstrong

(In reply to Takashi Iwai from comment #1)
> Is this a kernel regression, i.e. it worked in older distros?
> You can try to install the openSUSE-42.1 kernel on top of 42.2 system, for
> example, to see whether it works with 4.1.x kernel.

No, it's not a regression.  I tested with the 4.1.x series and had the same
behavior - middle button isn't recognized.  I guess Lenovo changed the hardware
and didn't tell us.
-Alex