someone told me this
The bounding box is displayed using an Ogre::WireBoundingBox object, which inherits from SimpleRenderable/Movable, which sets CastShadows to true by default. The WireBoundingBox object in scene node is protected, hence not accessible from the outside.
The solution would be that WireBoundingBox should default to CastShadows = false.
Take it or leave it. thanks