public class ScrollLayout
Similar to a javax.swing.ScrollPaneLayout, but not as restrictive on the
components that can be added. This layout is essentially a 3 x 3 grid layout,
with the intent that the bottom and right will hold scroll bars. When installed
a TextArea, the bottom has a scroll bar, the right has a vertical box containing
a scroll bar, the left has a Gutter, and the center holds a TextAreaPainter.
The corners and top are not used by the TextArea.
The corners are intended to be a place to put a button or other small component.
The corner dimensions are constrained by the left, right, top, and bottom
components, so, for example, the width of the top left corner is the width
of the left component and the height of the top left corner is the height of
the top component.