Hi !
So, I bought a MIDI control surface, KORG's Nanokontrol2. I thought it would be somehow plug and play with Reaper, but well... not so much. I found a few tutorials on youtube or this forum to make it work, but nothing worked as well as I hoped. So I wrote my own plugin, to have my Nanokontrol 2 work just the way I want it.
It now works just the way I wanted to. All buttons work, except for "Track previous" / "Track next" (what should I use them for ?). Reaper will send feedback and appropriately turn on/off the lights on your surface. The right-most controls are bound to the master (but you may change that).
If it may help, here it is :
https://github.com/Pierousseau/reaper_generic_control
Have fun with it, and feel free to give feedback