Feature request or maybe bug: have volume buttons always modify global volume

[glindsey]

This is somewhat related to #84, but is a bit more in-depth.

Here's the thing: right now, the volume buttons modify the overall system volume when in Launcher, but when in a RetroArch-powered emulator, they modify the volume inside RetroArch. The problem is that these two different volume options "stack" -- the volume inside RetroArch is dependent on the system volume.

This behavior can be demonstrated by turning the volume down very low in Launcher, then launching a RetroArch emulator, and then trying to change the volume inside the emulator. The maximum volume inside the emulator is entirely dependent on the system volume.

IMO, ideally the volume buttons would always do the same thing -- e.g. controlling the volume via @follower46's script when not in Launcher. This would provide the added benefit of being able to control the volume regardless of what happens to be running. One con of this is that you'd have no way to provide graphical feedback when pressing volume buttons outside of Launcher. A future GameShell HW revision incorporating some GPIO-controllable LEDs might alleviate this problem.

[Cecilectomy]

The thing is, the hotkey Shift+Start (add key +) and Shift+Select (subtract key -) which manage volume in the launcher GUI are the same default key bindings in Retroarch for its own internal volume management. Even if the launcher or some other script manages the system volume using those keys, afaik you would still need to unbind them in Retroarch and any other software that uses +/- for volume control.