Ability to choose to either clean up or keep the last frame of animation after an animation completes

Right now, the fade animation will retain its "last" frame after the animation completes, but the color-fade animation will reset to a "clean" state. Need the ability to let the user choose which one they want.
If keeping the last frame is chosen, also need a way to reset back to a clean state (possibly by running the animation in "reverse").
