In some rare cases, more complicated child models are used. The
RenderTable render object’s constructor takes an array of arrays of
children, the class exposes getters and setters that control the number
of rows and columns, and there are specific methods to replace
individual children by x,y coordinate, to add a row, to provide a
new array of arrays of children, and to replace the entire child list
with a single array and a column count. In the implementation,
the object does not use a linked list like most render objects but
instead uses an indexable array.

The Chip widgets and InputDecoration objects have fields that match
the slots that exist on the relevant controls. Where a one-size-fits-all
child model would force semantics to be layered on top of a list of
children, for example, defining the first child to be the prefix value
and the second to be the suffix, the dedicated child model allows for
dedicated named properties to be used instead.