Would like to be able to change appearance_flags on-step in animate().

Currently it is not a supported variable, though it is a variable you can set on a mutable_appearance, and you can set appearance = mutable_appearance in an animate() step. However, since appearance_flags are not supported in animate(), doing this currently just causes the appearance_flags to change before the animation sequence begins.

If animating these flags being removed is an option (not sure on what that would look like) that would be neat, but changing instantly on-step is enough for me personally.