A pane that displays a hierarchical list of items which (unlike tree-view) allows extended selection.
extended-selection-tree-view is like tree-view but allows more than one item to be selected at once.
extended-selection-tree-view is a subclass of collection, it does its own items handling and you must not access its
and related slots directly. In particular for
extended-selection-tree-view do not pass
:items-map-function, and do not use the corresponding accessors.
extended-selection-tree-view with the second argument being a list of the selected items, unless
:single-selection, in which case it behaves the same as in tree-view.
CAPI User Guide and Reference Manual (Windows version) - 25 Feb 2015