how to add tinymce listbox values in windowmanager

how to add tinymce listbox values in windowmanager

I open up a windowmanager and add a textfield and listbox:
editor.windowManager.open({
title: 'Insert caption',
body: [
{type: 'textbox', name: 'text', label: 'text', 'multiline':
'true', 'minWidth': 450, 'minHeight': 100},
{type: 'listbox', name: 'align', label: 'align', 'values':
['pull-left','pull-right']}
],
The listbox is displayed, but not the values. In the documentation
(http://www.tinymce.com/wiki.php/api4:class.tinymce.ui.ListBox) it states:
"Array with values to add to list box."
What am I doing wrong?