Collapses the section in which the sender resides into a single horizontally scrollable row.
- macOS 10.12+
The object that requested the action.
The icon view in Finder offers this type of collapsible section behavior when users choose the Show Less and Show More buttons. To enable this behavior, your header view must conform to the
NSCollection protocol, because the collection view uses the
section property to identify the button that controls the collapse action.