Two months ago I started contributing to PPSSPP the PSP emulator. Through sporadic patches of development my contribution of cross platform key mapping has taking shape. Just two minutes ago the latest visible tip of my work succeed in compiling. I present to all curious:

The “Set a new key mapping” screen now shows the most recent pressed key.

Getting this far has required crawling through multiple layers of ppsspp. It is a small victory yet sweet progress. I am gunning for the next major ppsspp release 0.9