The DevExpress ASP.NET List Box (ASPxListBox) editor allows you to select multiple list items at the same time. The editor's SelectionMode property controls selection behavior. Depending on this property's setting, the following selection modes are available within the ASPxListBox editor:
Single - End-users can select only one item within the editor.
Multiple - End-users can select multiple items within the editor by clicking list items while pressing Ctrl (to add an individual item) or Shift (to select a range of items).
CheckColumn - End-users can select multiple items within the editor by clicking list items.
When Multiple Selection is enabled, use the item's Selected property to specify individual items' selection state. Use the SelectedItems or SelectedIndices properties to obtain a collection of selected items. Also, to apply an item selection on the client side, use a specific client API (the editor's GetSelectedItems,
SelectItems, UnselectItems client methods).
When the CheckColumn selection mode is enabled for the list box, end-users can select all items using the "Select All" check box at the top of the list box. To enable this feature, set the ASPxListBox's EnableSelectAll option to true.
Note that in multiple selection mode, all ASPxListBox's features are supported, except loading items on demand via callbacks (which the editor's EnableCallbackMode and CallBackPageSize properties usually control).