http://www.mameworld.info/ubbthreads/showflat.php?Number=305674
Could we get something like this in Retroarch? 
Would be quite awesome with my new Lightboost LCD.
Looks like a driver option to me, and not something you’d have to support in the app itself. If some trivial things have to be done in the app, I’d like to see a pull request.
It IS a driver option to enable Lightboost on monitors that support it. However, to actually gain the motion blur reduction effect, Lightboost alone isn’t enough, you have to have a framerate of 120 fps - (or 100 fps). As mentioned in the post I linked, MAME solves this by inserting an additional black frame between rendering each normal frame, or, put differently, by making every other frame an additional black frame. For proper support, RetroArch would have to do the same. Might also be doable via a shader…
This would also provide a motion blur reduction on non-Lightboost 120 Hz LCDs.
Ideally 2-3 lines of code. I’d like to see a POC of it running first though. In D3D or GL driver, you can probably just swap/clear/swap instead of swap at end of frame call.
Some additional pages on this.