Oh, one more thought on the story-stick thing.
When you draw walls, ctrl and alt make it do different things. This could similarly be used to switch between a system hole and a drawer slide hole. Maybe alt makes an icon with a double-sided arrow (instead of a red triangle) for a system hole, indicating it draws a circle on two faces. For a drawer slide it’s a small single sided arrow, indicating a hole only on one face.
Joe, my wife says I’m full of it all the time. This must be what she means. I’m just full of ideas today! 🙂