If the AllowRowSizing property is True, the user can change the row height at run time. When the user places the mouse pointer over a row divider at the left edge of the list, 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 list will be resized to the same height; it is not possible to resize individual rows.
The RowHeight property of the list 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 list in code, even if AllowRowSizing is False or you cancel the RowResize event.