However the FX only supports these 256 constants and every other NV card above the FX doesn't need the fixup since ARB_texture_non_power_of_two is supported in hardware.
This was my thought when limiting the index array to uchars. I know that you mentioned we could use the fixup code also for older cards, but in this case: even fewer constants. So it doesn't make much sense for me to allow indices greater than 255.
