This problem caused because osgManipulator::Dragger uses matrices of top camera instead last
absolute Camera in NodePath.
I attached modified osgManipulator/Dragger.cpp file, where added code for finding last absolute
camera. With this changes draggers works in HUD.
Example for demonstrate this problem you can find in osg-users list [1].
Mikhail.
[1] http://thread.gmane.org/gmane.comp.graphics.openscenegraph.user/62636
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