[away3d] Change pushback at runtime?

[joebass]

When the camera is moved to a certain area of my scene, I'd like to
change the pushback and ownCanvas properties of a couple
ObjectContainer3D's.  I've tried with

frontCornerModel.ownCanvas = true;
frontCornerModel.pushfront = true;
frontCornerModel.updateObject();

but, it doesn't have any effect.