IDEA every layer can have an opacity value from 0 to 1. every clip, path, text, etc, would display at it’s current frame’s layer’s opacity value present of it’s own opacity value.
opacity = this.opacity/this.Frame_im_on.Layer_this_frame_is_on.OpacityValue
(it probably wouldn't be this simple to do, but still)
It would make making finished animations way easier.