Application users often want to make single
and
multiple selections from a list. Some of the time they want a new selection to deselect the previous one, so that only one selection remains -- just like a
:single-selection
panel. On other occasions, they want new selections to be added to the previous ones -- just like a
:multiple-selection
panel.
The
:extended-selection
interaction combines these two interactions. Here is an extended-selection list panel:
(contain
(make-instance
'list-panel
:items '("Item" "Thing" "Object")
:interaction :extended-selection))
Before continuing, here are the definitions of a few terms. The action you perform to select a single item is called the
selection gesture
. The action performed to select additional items is called the
extension gesture
. There are two extension gestures. To add a single item to the selection, the extension gesture is a click of the left button while holding down the
Control
key. For selecting a range of items, it is a click of the left button whilst holding down the
Shift
key.