Two Layout Managers.

1. FloatCenterLayout - center a single child component in the center of the parent.

   This layout is used to float the initial text "click on document to view ..." in the center of the DVI Controls window.

2. RegularLayout - a simple grid layout class. All grid cells have the same width and height, but children can span several cells. By default the number of cells is determined by the placement of the children, but a specific rectangle of cells can be specified instead. One row or column of the grid can be allowed to soak up all extra space.

   This class is used to implement the button bar at the top of the DVI controls window. The buttons are two cells wide, the text entry field is three cells wide, and groups are separated by a single cell. The next-to-last column is stretchy.