I am wondering if following statements are true:

* `active_object` is always identical to `object`.
* `active_object`(or `object` if previous statement is true) is always the first one of `selected_objects`. (This seems to be a false statement since if I use `bpy.ops.object.select_all(action='DESELECT')` the `active_object` and `object` is not changed while `selected_objects` is empty.)