Sawfish specific configurable pager map of your desktop with a viewport support. It can be configured to follow where you are, or optionally show all workspaces at once.
A pager is a map of your desktop. As maps go, it shows not only the visible part (your current viewport), but if you are so configured, also the parts that extend beyond the sides of your screen. Also, if you have more than one workspace, the pager will follow you to where you are, or optionally show all workspaces at once. Of course you can select viewports and windows, and also move or raise/lower the latter.
Check README from this package documentation how to activate.