i like the option to have drawing object art layers be “flat” or have their individual strokes and elements on yet another, internal sub-stack of layers within that single art layer. from what i can determine, though, once an art layer is flattened (or has been drawn out using the “auto flatten” toggle), those flattened strokes and shapes cannot be separated back into the separate sub-stack layers again.
it would be very helpful to be able to select parts of a merged outline shape and (un-flatten? de-flatten? un-merge?) the selected elements into another sub-layer of this internal stack in the current art layer, without having to break the selected parts into a different drawing layer/object. then could use the normal “arrange” controls to set the visible order as normal.
i feel like this separation action would be primarily useful for pencil strokes that may intersect in unwanted ways, etc. this happens often for me – i want to start dragging the control points of some pencil strokes that i have on an art layer and they are forming unwanted joints at the intersection areas of other pencil strokes. breaking apart a glob of flattened brush shapes would understandably take more preparation by the user and would probably be more difficult to develop the toolset for it.