The last topic that we have to cover is the layout managers. So far we've worried only about each specific class and what it does and we haven't been worried about how the fields are arranged on the screen. This task falls to the managers.
There are three managers provided by the SDK that handle most normal situations—VerticalFieldManager, HorizontalFieldManager, and the FlowFieldManager. Each of these managers arranges the fields within them differently. The names make their roles pretty clear. A VerticalFieldManager arranges the fields veritcally, or stacked on each other, as we have seen in the sample applications we have built so far. The HorizontalFieldManager arranges fields horizontally on a single row. In contrast to this, a FlowFieldManager arranges the fields horizontally and vertically by wrapping fields from one line to the next line.
A MainScreen class has a VerticalFieldManager built into it, which is one of the reasons that we are using it. When we call the...