__init__(value, choices, options) {
		this.super('__init__', [ value, choices, Object.assign({
			select_placeholder: _('-- Please choose --'),
			custom_placeholder: _('-- custom --'),
			dropdown_items: -1,
			sort: true
		}, options, {
			multiple: false,
			create: true,
			optional: true
		}) ]);
	}
Comboboxes support the same properties as
[Dropdown.InitOptions]{@link LuCI.ui.Dropdown.InitOptions} but enforce
specific values for the following properties:

@typedef {LuCI.ui.Dropdown.InitOptions} InitOptions
@memberof LuCI.ui.Combobox

@property {boolean} multiple=false
Since Comboboxes never allow selecting multiple values, this property
is forcibly set to `false`.

@property {boolean} create=true
Since Comboboxes always allow custom choice values, this property is
forcibly set to `true`.

@property {boolean} optional=true
Since Comboboxes are always optional, this property is forcibly set to
`true`.