libretro/gambatte-libretro — pull request #25 by Alcaro (2014-06-05 23:44:11+00:00)
Title: Add a core option for GBA mode.

For use with the Zelda Oracles, and two or three other games too I guess. The button exists, no reason to not expose it all the way up to the user.
The easiest testcase is Shantae; if the colors get considerably brighter and the title screen says GBA Enhanced right beside Press Start, it works.