simple-pinboard-layout is a pinboard-layout that can contain just one pinboard object or pane as its child, and it adopts the size constraints of that child.
simple-pinboard-layout is normally used to place pinboard objects in a layout by placing the layout inside a
simple-pinboard-layout, thus displaying the pinboard objects. It inherits all of its layout behavior from simple-layout.
CAPI User Guide and Reference Manual (Macintosh version) - 25 Feb 2015