Dell Venue 11 Pro 7140 - Volume buttons not working with kiosk shell

Hi,

We have several Dell Venue tablets that are used to run interviewing software. We  use a shell/kiosk that loads instead of the windows 8 desktop in order to lock down the tablet and restrict what runs on the device. With the shell running the volume control buttons on the side of the tablet are not functional, I assume they are mapped to the windows gui/desktop therefore not visible from the shell software.

I was wondering if you could tell me how the OS sees the volume keys and whether we can capture the input from them to restore volume control from with our shell software.