End-users can collapse and expand a category row or a parent row using the expand or collapse button. Use the SetRowExpanded method to programmatically expand a row. To get the row expanded state on the client side, use the GetRowExpanded method.
To specify the collapse state of the particular row, use the GetRowExpanded and SetRowExpanded methods.
On the server side, the window collapse state is controlled by the VerticalGridHierarchicalRow.Expanded property.