Even if this doesn't get solved, I think it would still be worth updating the library. There are a few fixes and improvements that we could benefit from.
Btw, I noticed the library can receive the red, green, yellow and blue (BD_VK_RED, BD_VK_GREEN, BD_VL_YELLOW, BD_VK_BLUE) button presses, passed to it the same way the up, down, left, right button presses are passed to it (BD_VK_UP, BD_VK_DOWN, BD_VK_LEFT, BD_VK_RIGHT). The key constants are defined in src/libbluray/keys.h.
This would make it possible to implement the BluRay menu color buttons feature, by sending these keys to the library on receiving the USB Consumer Menu Controls 69 to 6C (Red/Green/Blue/Yellow Menu Button) key presses. (a multimedia keyboard is both a USB Keyboard and a USB Consumer Control device - the Play/Pause, Stop, Volume Up, etc. keys are sent as Consumer Control key presses not as Keyboard key presses; the USB receiver of a remote is also a USB Consumer Control device, and sometimes a USB Keyboard too, and will send Consumer Control key presses when the Red/Green/Blue/Yellow keys of the remote control are pressed just as it sends Consumer Control key presses when the Volume Up, Volume Down, Play, Stop keys are pressed on it).
The USB Consumer Controls are listed in the Universal Serial Bus HID Usage Tables (
link).