To use the navigation window, be sure that the
  namespace display is in tree format and then drag the
  slider on a scroll bar. The navigation window contains
  a reduced image of the currently expanded part of the
  namespace.

  To move around in the namespace, point anywhere in the
  navigation window and drag the mouse to move the box
  that is inside the window. When you release MB1, the
  portion of the namespace surrounded by the box appears
  in the Browser window.

  Click on the button at the bottom right corner of
  the Browser window to make the navigation window a
  separate, permanent window. Click on the same button to
  close the window.