Creates a RowColumn widget. Returns the widget name.
This widget is only used to force its children to be
laid out in rows and columns.
-packing NONE | COLUMN | TIGHT (CS)
Sets how items contained in a RowColumn widget are packed.
No packing is performed. The x and y attributes
of each entry are left alone, and the column
widget attempts to become large enough to enclose
All entries are placed in identically sized boxes.
The boxes are based on the largest height and width
values of all the children widgets. The value of
numColumns determines how many boxes are placed
in the major dimension, before extending in the
Given the current orientation (horizontal or
vertical) entries are placed one after the other
until the RowColumn must wrap. A RowColumn will
wrap when there is no room left for a complete
child in that dimension. Wrapping occurs by
beginning a new row or column in the next available
space. Wrapping continues as often as necessary,
until all of the children are laid out. In the
vertical dimension (columns), the boxes are set to
the same width; in the horizontal dimension (rows)
the boxes are set to the same depth. Each entry's
position in the major dimension is left unaltered;
its position in the minor dimension is set to the
same value as the greatest entry in that particular
row or column. The position in the minor dimension
of any particular row or column is independent of
all other rows or columns.