Box nodes are container nodes for item nodes.  Box nodes are
specified as follows:
<box orientation="alignment" min-width="num" xpadding="num"
ypadding="num" spacing="num" homogeneous="bool">
Where "num" means number and bool means either "true" or "false".
The alignment value can be either "horizontal" or "vertical".
If you leave any property off it will default to zero or "false" in
case of "homogeneous", and "vertical" for the orientation.
If the box is homogeneous then the children are allocated equal
amount of space.
The "min-width" must be specified in pixels.  Obviously there is
also a corresponding "min-height" property as well.
