If the AllowRowSizing property is True, the user can change the row height at run time. When the user points to a row divider in the record selector column, the pointer changes to a vertical double arrow, which the user can drag to adjust the height of all rows.
Dragging the pointer upward makes the rows smaller; dragging it downward makes the rows larger. All rows in the grid will be resized to the same height; it is not possible to resize individual rows. If the grid does not display the record selector column (that is, the RecordSelectors property is False), users cannot interactively change the row height.
The RowHeight property of the grid will be adjusted when the user completes the resize operation.
You can prevent row resizing from occurring at run time by setting the Cancel argument to True in the RowResize event. You can always change the RowHeight of the grid in code, even if AllowRowSizing is False or you cancel the RowResize event.