From Xojo Documentation
If True, you can reorder rows within the ListBox by dragging rows.
An insertion line indicator appears when dragging within the ListBox to provide you with visual feedback as to where the row would be dropped if you release the mouse button.
|You cannot drag rows on a ListBox with expandable rows (hierarchical) and as a result, setting this property to True has no effect.|
This example enables the drag reorder feature.