which could fix the dragger size in screen, so that no matter how we
zoom in/out the camera, the dragger will never be scaled.
This is what 3D graphics software like 3dsmax and maya behave, which
helps users select and manipulate draggers more easily.
You may turn on the feature with the new --fixedDraggerSize argument:
# osgmanipulator.exe --fixedDraggerSize --dragger TranslateAxisDragger
cessna.osg
"