[TYPO3] Draft Workspace: New pagecontent on subpage is not referenced to subpage

[Christian Rubbert]

Hey,
I've got a problem with workspaces, I've created a user and gave him 
access to edit in the Draft Workspace, then:

1) The user creates a subpage
2) The user creates content on that subpage

That newly created content is not automatically referenced to the 
subpage, i.e. the user cannot see it when he previews the page.
When I manually add it to the "content" box of the subpage, the content 
is shown in the preview. (I attached a small screenshot to clarify what 
i mean by "content box")

I thought of permission problems first, but actually the same happens 
with my admin user.

Googling, IRC and cross-reading Inside Typo3 didn't give me an insight, 
can anyone point me in the right direction?

mfg,
Christian Rubbert