Restoring display

[Rich Shepard]

I'm running version 2.3.6.1.  LyX format is 544.

The content environments are not visible in the outline pane. Under the
Outline heading is the dropdown box that normally has environments such as
Standard, Section, and so on. Now the widget displays Table of Contents and
the other items available are Citations, Figures, Footnotes, Graphics,
Labels and References.

I don't know what I did to get this display so I've no idea how to return it
to return it to what it's been before.

A clue stick is needed.

Rich