The DataGridListData class defines the data type of the listData property that is
implemented by drop-in item renderers or drop-in item editors for the DataGrid control.
All drop-in item renderers and drop-in item editors must implement the
IDropInListItemRenderer interface, which defines the listData property.
Although the properties of this class are writable, you should consider them to
be read-only. They are initialized by the DataGrid class, and read by an item renderer
or item editor. Changing these values can lead to unexpected results.