public boolean containsGui(BoundingVolume bound) {
        if (bound == null) {
            return true;
        }
        return guiBounding.intersects(bound);
    }
Tests a bounding volume against the ortho
bounding box of the camera. A bounding box spanning from
0, 0 to Width, Height. Constrained by the viewport settings on the
camera.

@param bound the bound to check for culling
@return True if the camera contains the gui element bounding volume.
jme3-core/src/main/java/com/jme3/renderer/Camera.java