Simple talk about SetBuddy between IToobarControl and AxToobarControl.

Discussion created by kjulistened on Oct 11, 2013
I heard one saying "ArcEngine communicates using interface", but I am not sure whether it is the same here.
You may saw the code about "MapAndPageLayoutSynchApp" in the "Sample" of the ESRI document.
What confused me is that why it use the SetBuddyControl method of "IToolbarControl" instead of the method in the class "AxToolbarControl".
I posted this issue because the method in the AxToolbarControl use the instance of "IToolbarControlDefault ",which always keeps the newest version, isn't is? If so,way it use that way?
Could you launch me something about this? Thanks very much.