Hi there.
I think what you're looking for are control panel views. A few that pop up in my head are: Johnny5 (J5) from Howard Casto and CPviewer. I use J5.
What they do is that, using a controls.dat file you can view which button do what. Very ingenious really.
They are not front-end exclusive, but they do need a bit of thinkering to be used from within the emulator itself (you need an ahk script). Just do a search for j5 or cpviewer in the forum; believe me, there's a lot of info here.
Sorry that I couldn't help more.
Cheers,

Congui