Allow NULL selection


This property specifies if the Button List allows all controls to be de-selected after an initial selection is made.

The "auto" setting means that the ButtonList behaves like a RadioButton control (if the Allow multiple selection property is turned off) or like a Checkbox Control (if the Allow multiple selection property is turned on). A Radio Button control does not allow a user to 'deselect' all radio buttons once a selection has been made. On the other hand a checkbox allows you to deselect all choices so that there are no checkbox controls. With the "true" setting you can always deselect everything even after making a selection (regardless of the setting for Allow multiple). Using the "false" setting means that you can never deslect everything after making an initial selection.

Set to "true" with button selected
Set to "true", button can be deselected
Set to "false" with button selected
Set to "false", button can not be deselected
On "false" with "Allow multiple selection" off
Setting Allow NULL selection to "false" with the "Allow multiple selection" property turned off will result in a ButtonList where one button is always selected.