Rodot:
The battery monitoring system (aka "no battery, please turn off") is a pain when running with usb-power only, because every single program built on gb lib will not function. And, as ENABLE definition for the battery monitoring is only available as a compile time switch, a usb-only user will need to re-compile all the official binaries before they can be used.
The way that the battery monitoring is built (monitors voltage level on ADC6) means that there is NO way to bypass it / fake it on a 28-pin DIP atmega328. I have investigated this thoroughly, and it is so. Pins adc6 and adc7 are "floating" in the 28-pin DIP version and there is nothing that can be done about it.
Could you please come up with a run-time (not compile time) setting to disable the battery monitoring ? I know it will require work, for example an extra entry in the settings page on PROGMEM. But consider the fact that "Gamebuino on breadboard" with 28-pin DIP part is now impossible to get working without having to recompile all programs.
I think this change, if done, would be a good idea to do now when the library is in its early stages.