Prevent manual creation of documents in certain folders

At the moment, it's not possible to prevent users from manually creating documents of any type in a certain folder.

One can limit the allowed types to one or more using the method described at http://www.onehippo.org/cms7/documentation/development/extending+CMS7/user+interface/document+types+in+folder.html

But defining no (0) types, results in all types being listed in the folders workflow menu.

The only way to do this, is define an non-existing type (e.g. "none"). The plugin will not find the type and will not display it in the menu, however a warning is logged:

01.07.2010 14:03:39 WARN [org.hippoecm.repository.standardworkflow.FolderWorkflowImpl.prototypes():126] Unknown folder type none

There should be a more elegant way to do this.