We build a Windows client application for SharePoint online with SharePoint Client Object Model. We want to use OAuth to authentication for this Windows Client application, but we didn't find a way to do it; and the docs on MSDN is ambiguous.

This [article](http://blog.scoreman.net/2013/02/create-site-collections-in-sharepoint-online-using-csom/) gives an example, however, when I create the new application with the link `https://<TENANT>.sharepoint.com/_layouts/appregnew.aspx`, the option of "An app running on a client machine" is disabled, is there a setting in SharePoint online site to enable this?