Tbh, I'm not sure. The AltGr key is a bit of an odd one and it can depend on the keyboard what it actually represents. Technically, iirc, it should really be the combination of LControl + LAlt that results in the AltGr key, but as GM VK constants are for SINGLE keys only, it could be that it simply returns Control. If you want to check left/right alt keys, maybe test using keyboard_check_direct, as that should - in theory - return them independently. Note though that the function is only useful on the Windows target.