Library /sys$common/syshlp/dce$cdsbrowser.hlb Overview, navigate_ns, index_window  *Conan The Librarian (sorry for the slow response - running on an old VAX)

  When the namespace is in outline format, dragging the
  slider up and down the vertical scroll bar produces an
  index window. The index window shows the name where the
  slider is currently positioned in the namespace.

  When the index window contains the name you want to
  view, release the mouse button MB1 to position that
  name at the top of the Browser window.