From Fedora:

  https://bugzilla.redhat.com/bugzilla/show_bug.cgi?id=143154

  The workspace switcher application indicates the current workspace
  by coloring the background and coloring the active window.

  However, with full workspaces the background can become completely
  obscured.

  Additionally, the active application may be too small to make any
  significant indication on the workspace switcher. (It can even
  be entirely obscured).

  Steps to Reproduce:
  1. Open many windows completely obscuring multiple workspaces
  2. Make some tiny window active
  3. Look at the workspace switcher to try to determine where you are.
    
  The current workspace should be made alwayys discernible. A useful
  invariant would be for the number of "indicator pixels" to remain
  constant regardless of the state of the various workspaces.

  One idea is to fade all but the current workspace or something similar.