Using existing masks
When altering a new mask through adding, subtracting or intersecting we should be able to select an existing mask. Often existing masks have multiple addition, subtraction and/or intersection adjustments. If we want to use one of these existing masks it has to be manually recreated in the new mask.
In the AI masking of people or (now) landscapes we can subtract any of the generated masks. We should be able to select any existing mask in the list of masks for that file as a pulldown menu.
