How can I paint and animate a mask with the new Grease Pencil? does anyone know how to paint (and animate) a mask within the new Grease Pencil (Blender 2.8) ?

I guess that it should be possible to either define a Grease Pencil layer as mask; or to use an holdout material or something ?

Thanks !
Using Subtract as a Blend mode for a Grease Pencil layer acts just like a mask:



Subtracted layers will act as holdout for every other layer that is listed below them, but regardless of their view-depth (layers in front are masked out too). Layers in other GP objects are not affected