Hi everyone! I’m developer, and i have a question. I want to develop my own GUI for RetroArch via Qt (something like this) . So, first question, where can i find information about API, it is desirable that is was manual or example? Secondly, may exist special forum for developers? Thirdly, can i get retroArch only by build is from source (i use this manual), i mean can i install this via PPA?
Thank you.
P.S. Sorry for mistakes 
There are two PPAs on launchpad, testing and stable: https://launchpad.net/~libretro
The libretro API is pretty easy to implement a frontend for, and there is an OpenEmu-like Qt5 frontend under construction called Phoenix: https://github.com/team-phoenix/Phoenix
However, it sounds like you’re actually wanting to make a launcher for RetroArch, which is much, much easier and leverages RetroArch’s pre-existing strengths (shaders, input/output drivers, etc.). EmulationStation, which is included in the RetroPie project, is such a launcher.
Lakka is special insofar as its GUI is being integrated into RetroArch as a built-in “menu driver,” which is a more difficult task than creating an external launcher.
Actually, i’m wanting to make a simple menu for emulators on Raspbian. Maybe exists easy way to make this? I need something like this -> user pick Super Mario on NES in my menu via Qt, and then i launch FCEUX, for instance, with Mario. I don’t need all consoles, i think NES & Sega is enough for me.