The “Summary View”, located at the bottom of the edit window, is a condensed view of the entire session between the “start” and “end” markers.
By default, the Summary view is not shown. But you can enable it by visiting the “View” menu.
Within the Summary view you can see a small representation for each audio/midi region on the timeline, and a lightly shaded box that indicates your current edit canvas view. You can grab the light shaded box to pan up, down, left, or right. And you can grab the edges of the light shaded box to stretch or shrink (zoom) in either dimension. Additionally, arrow buttons are provided at either end of the view box for maneuvering the shaded box if you prefer.
The height of the view box can be made larger or smaller by grabbing its top border and dragging.
In the image above three regions are shown with the shaded box fully encompassing the region contained in track 2, indicating it will be fully visible in the edit canvas. The start of regions 1 and 3 will not be visible but the regions ends will be.