If the AllowRowSizing property is set to either RowSizingEnum.AllRows or RowSizingEnum.IndividualRows, the user can change the row height at run time.

When the user points to a row divider between any pair of checkboxes, the pointer changes to a vertical double arrow, which the user can drag to resize the row.

Dragging the pointer upward makes the rows smaller; dragging it downward makes the rows larger. If the property is set to AllRows, then all rows in the list will be resized to the same height; it is not possible to resize individual rows. If the property is set to IndividualRows, then each row can be sized independently.

The ItemHeight 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 ItemHeight of the list in code, even if AllowRowSizing is RowSizingEnum.None or you cancel the RowResize event.