tjwei/xnes — pull request #1 by jancborchardt (2012-09-25 19:24:27+00:00)
Title: map key Y (in addition to key Z) to button Y, for international keyboards

There are some countries such as Germany where the Z and Y keys are switched around: https://en.wikipedia.org/wiki/Keyboard_layout#QWERTZ

To not need to hold your hand in such a weird way, not only Z but also Y is mapped to the Y button.