/usr/include/Inventor/draggers/ is in inventor-dev 2.1.5-10-16ubuntu1.
This file is owned by root:root, with mode 0o755.
..
/usr/include/Inventor/draggers/SoCenterballDragger.h
/usr/include/Inventor/draggers/SoDirectionalLightDragger.h
/usr/include/Inventor/draggers/SoDragPointDragger.h
/usr/include/Inventor/draggers/SoDragger.h
/usr/include/Inventor/draggers/SoHandleBoxDragger.h
/usr/include/Inventor/draggers/SoJackDragger.h
/usr/include/Inventor/draggers/SoPointLightDragger.h
/usr/include/Inventor/draggers/SoRotateCylindricalDragger.h
/usr/include/Inventor/draggers/SoRotateDiscDragger.h
/usr/include/Inventor/draggers/SoRotateSphericalDragger.h
/usr/include/Inventor/draggers/SoScale1Dragger.h
/usr/include/Inventor/draggers/SoScale2Dragger.h
/usr/include/Inventor/draggers/SoScale2UniformDragger.h
/usr/include/Inventor/draggers/SoScaleUniformDragger.h
/usr/include/Inventor/draggers/SoSpotLightDragger.h
/usr/include/Inventor/draggers/SoTabBoxDragger.h
/usr/include/Inventor/draggers/SoTabPlaneDragger.h
/usr/include/Inventor/draggers/SoTrackballDragger.h
/usr/include/Inventor/draggers/SoTransformBoxDragger.h
/usr/include/Inventor/draggers/SoTransformerDragger.h
/usr/include/Inventor/draggers/SoTranslate1Dragger.h
/usr/include/Inventor/draggers/SoTranslate2Dragger.h