Items that build the drop-down list.
| children | The list of child items of this item. |
| enabled | True if the item is enabled. |
| icon | If set, this icon will be rendered to the left of the item name. |
| id | The unique identifier for an item. |
| name | Name shown for this item when rendered. |
| AddChild | Adds the given AdvancedDropdownItem child to the children list. |
| AddSeparator | Adds a separator to the list of children in the drop-down. |