listboxes

A listbox is a graphical control that displays a list of items from which the user can select one or more options. Items are usually shown in a vertical list and the view can be scrollable when the number of items exceeds the available space.

Listboxes come in single-select and multi-select variants. In single-select mode, only one item can be chosen; in multi-select mode, multiple items can be selected either by using keyboard modifiers (such as Ctrl or Shift) or by interaction with checkable items, depending on the platform or framework. The control may also support features such as item grouping, sorting, or custom item rendering.

Common properties and data handling include a collection of items, a selected item or index for single-select configurations, and selected items or indices for multi-select configurations. Some implementations support data binding to a data source, as well as events such as selectionChanged or change, which notify when the user alters the selection. Customization often allows item templates, styling of the selected state, and virtualization to handle large item sets efficiently.

Interaction and accessibility considerations emphasize keyboard support and screen reader compatibility. Typical navigation includes moving focus with the Up and Down arrows, jumping to the beginning or end with Home or End, and selecting with Space or Enter. ARIA roles may designate the control as a listbox with options, aiding assistive technologies.

Compared with other controls, a listbox displays all options for direct selection, unlike a combo box, which shows options in a collapsible dropdown. Listboxes are commonly used for selecting multiple items or when the set of options is lengthy.