This idea comes from Zoomnotes a digital writing program that I use occasionally. What this feature does it allows the user to drag and drop pieces of text off the page and puts it on the blank space out off the margins of the page. The benefit here is you can drag and drop that text back onto the writing page when you need it.
This idea would work nicely in ASP. What this does is it allows the user to transfer the artwork by selecting everything on the page and dragging it onto the blank backspace out of the canvas ready to be dragged back onto the canvas when needed. Why would this be needed? Think of the benefits.
1. You won't have to delete the artwork right away to start from scratch. The art now becomes a impromptu repository of ideas you can "put aside" like a grab bag.
2. Then blank space surrounding the canvas becomes your stylesheet allowing you to reuse the same artwork when needed. For example, let's say you need to add some sky elements to the page. Instead of painting over an area with blue skies...you can "reuse" the sky you painted a while back since it's sitting off on the blank space. This saves time.
3. It would be the one area that ASP could get ahead of Procreate. Win win.