A MultiListBox item is used to place a list box in the rollout. This is a variant of the ListBox in which multiple items in the list can be selected. The syntax is:

MultiListBox <name> [ <caption> ] [ items:<array_of_strings> ] \
[ selection:{<bitarray> | <number_array> | <number>} ] \
[ height:<number> ]

The default alignment of MultiListBox items is #left.


rollout test "test"


MultiListBox mlb "MultiListBox" items:#("A","B","C") selection:#(1,3)

on mlb selected val do format "selected: % - %\n" val mlb.selection[val]

on mlb doubleclicked val do format "doubleclicked: % - %\n" val mlb.selection[val]

on mlb selectionEnd do format "selectionEnd: %\n" mlb.selection


rof=newrolloutfloater "tester" 200 300

addrollout test rof,3){}



The array of text strings that are the items in the list.


A BitArray signifying the currently selected items in the list. The default selection value is #{}.


The overall height of the MultiListBox in number of item lines. Defaults to 10 lines. To have a  MultiListBox display exactly N items, set height to N.


<listbox>.items Array of Strings

The item string array.

<listbox>.selection BitArray

The currently selected items. When setting the selection via a script, the selection can be specified as a BitArray, Array of numbers, or a number. If the items list is an empty array, this value is 0.


on <listbox> selected <arg> do <expr>

Called when the user selects or deselects an item in the list. The <arg> argument contains the index of the item that was selected or deselected. Since multiple items can be selected or deselected at once,  this handler is called for each item in the list, starting from the top of the list, whose selection has changed.


on <listbox> doubleClicked <arg> do <expr>

Called when the user double-clicks on an item in the list. Note that the on selected handler is always called on single clicks and on the first click of a double-click. The <arg> argument contains the number of the item double-clicked.


on <listbox> selectionEnd do <expr>

Called when the user selects or deselects an item in the list, but after all the calls to the on  selected handler have been made.


There isn't a way to deselect all the items in the list by clicking in the list somewhere. To clear the list selection you will need a "Clear Selection" button that sets selection=#{}.