All choices have a selection interaction, controlled by the :interaction initarg. The radio-button-panel and check-button-panel are simply button-panels with their interactions set appropriately. The interaction possibilities are listed below.
Set :interaction to :single-selection to force single selection. Only one item may be selected at a time: selecting an item deselects any other selected item.
Set :interaction to the value :multiple-selection to create a multiple selection choice element. This lets you select as many items as you want. A selected item may be deselected by clicking on it again.
Set :interaction to the value :extended-selection to create an extended selection element. This is a combination of the other two: Only one item may be selected, but the selection may be extended to more than one item.
Set :interaction to the value :no-selection to force no interaction. Note that this option is not available for list panels. To display a list of items with no selection you should use a display pane instead.
Specifying an interaction that is invalid for a particular choice causes a compilation error.
The accessor choice-interaction is provided for inspecting a choice's interaction.