Summary: Zoom out to see the entire layers list and timeline as a scalable screen grab - snapping back to normal view with a single Left Mouse Button click.
Description: Holding down Space + Option + Control gives access to Ultra Zoom. By then holding down LMB and dragging left or right zoom in and out from Normal View to Full View of the entire layers list and timeline. (What is actually happening is that AE takes what is essentially a screen grab of the current layers list and timeline and this image is being scaled- not the layers list and timeline itself).
Within this Ultra Zoom view you can also pan around from any zoom height (holding Space and dragging with LMB).
Clicking on an area of the view with a single LMB click will snap the view back to Normal View centring on the area you clicked.