Size Calculations

• minimumSize() is set by the object's native implementation peer e.g. MButtonPeer sets minimumSize() as label width + 14, label height + 8.
• preferredSize() defaults for Motif to minimumSize() in MComponentPeer.
• If there is no peer, these are set from the object's width and height. (Peer can be removed by Component's removeNotify() - but may be best to just override these methods?)