If you shrink a topic, then only its first line is displayed, except when you select text inside the topic, at which point the whole topic is shown. Thus, the topic is shown as a single line, except when you’re explicitly editing it. This can save considerable space in a document window, and simplifies display of the outline.
The illustrations below show a topic in its normal state (grown) and with just the first line displayed (shrunken). A shrunken topic is indicated by three dots near the bottom of its triangle.
To shrink a topic:
To grow a shrunken topic:
The menu commands mentioned above (Topic > Shrink Topic, Topic > Grow Topic) can be reduced to a single menu item in the Topic menu through a preference. These commands are available also through the contextual menu that appears when you Control-click on a topic’s triangle.