QT Quick QmlDesigner Plugin Missing in QT Creator

[Flesh]

In QT Creator I click on Help -> About Plugins... and under QT Quick I would expect to see QmlDesigner, but its missing.
"Reference: ":http://qteveloper.blogspot.com/2010/06/qt-quick-designer.html

OS: Ubuntu Studio 11.04 x64
QT Version in Ubuntu Repository: 4.7.2
QT Creator Version in Ubuntu Repository: 2.1.0

Install command line:
@
sudo aptitude install -y qt4-designer qt4-dev-tools qt4-demos qt4-doc-html qt4-doc qt4-qmlviewer qt4-qtconfig qtcreator cmake-qt-gui kuiviewer libqt4-core libqt4-gui libqt4-sql-tds libqt4-webkit libqt4-assistant eclipse eclipse-cdt
@

Also, do you know of a Repo/PPA for the latest version of QT?
Or do I need to clone it?
"Reference: ":http://qt.gitorious.org/qt/qt
"And":http://lists.debian.org/debian-qt-kde/2011/03/msg00156.html

Update: Maybe this is the reason: "Still Experimental":https://bugs.launchpad.net/ubuntu/+source/qtcreator/+bug/668858

I installed it from the SDK; works great; its just the packages for Ubuntu doesn't have experimental or non-stable releases.
Thanks

[tobias.hunger]

You will need to ask the ubuntu developers for details here. They did the packages, we have nothing to do with what they put into them or which option they use to build their deb files.

[ThomasHartmann]

The QmlDesigner in Qt Creator 2.1 requires some private headers from Qt. If these private headers are not present then the designer is not build.

Propably the Qt the Ubuntu packages are build with comes without private headers.