Code review comment for lp:~macslow/unity/unity.fix-863230

This sounds like a classic use-case for a Clamp.

See tests/test_properties.cpp in nux.

If we changed alpha and saturation to be properties with a clamp, you wouldn't have to manually check them.

However that would change all uses of RenderArg, and I'm not sure if that is desirable.

Due to the visual nature of this, I accept that we can't have automated tests for it.

We do however want design signoff, so getting John to look.