Zones should have inviolate borders - they should not interfere with each other. Zones should be arranged in a way that accords with Position Reflects Relationship . Text in that line is thus ambiguous. Beck has alluded to a pattern Split Into a Small Number of Zones that is probably related. A window divided into zones.
Many objects compete for screen space.
Make the space for a zone proportional to the importance of the objects and relations in that zone. A spreadsheet devotes most of the screen space to the user's data. The screen is small, and the various indicators take up almost half the screen space, leaving little room for editing - the main task. People will tend to focus on the middle. Put less important information surrounding it, on the edges.