




All choices have an interaction style, 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.