Implements basic selection API.
| getSelectedId | returns the id(s) of the selected item(s) |
| getSelectedItem | returns selected object |
| isSelected | checks whether the specified item is selected or not |
| select | selects the specified item(s) |
| selectAll | selects all items or the specified range |
| unselect | removes selection from the specified item |
| unselectAll | removes selection from all items |
| onAfterSelect | fires after an item has been selected |
| onAfterUnSelect | fires after an item has been selected |
| onBeforeSelect | fires before item selection has started |
| onBeforeUnSelect | fires before unselection of an item has started |
| onSelectChange | fires after selection state was changed |
| multiselect | enables multiselect mode |
| select | enables/disables items selection or multiselection in widgets |