it's a general problem of the driver... that's why MESS prompts at start a red screen saying that the graphics emulation is not 100% working
additionally, the graphical emulation has regressed at a certain point due to some changes in the MAME core (the road in Super Mario Kart was present before, iirc).
however, all these graphical issues are covered by the starting message and no reports are necessary at the moment except if * a game crashes or if * a game with no special chips doesn't even start
