Command buttons
- Contents -- displays the first section, normally a contents page.
- Search -- pops up a dialog box. The user may type a string (or an asterisk)
into the text item, press Do Search, and click one of the
matching section headings displayed in the listbox.
- Back -- goes to the previously-visited section or block. This works across
different files, since the recorded history includes file names.
- << -- goes to the previous sequential section.
- >> -- goes to the next sequential section.