Surface Pro Control Mapping

[thettooo]

Hi,

Does anyone know how to map the Up and Down Surface Pro 2 volume butons as key to the L and R on the emulator ?

It works on my Galaxy S3 but on my Surface Pro 2, when I push one off the two volume buttons on the control mapping screen of PPSSPP it only change the computer volume and do not change the key on the emulator.

If someone knows how to do...

Thanks !